Firefox Multi-Account contains are awesome for software development and testing! At my work we usually work at tools which have three roles: user, reviewer, administrator so I generally have three containers for these user accounts. This means I can be logged in with all the accounts I need for testing in the same web browser without resorting to private mode (which does not remember cookies between sessions anyway).
In addition, I use the temporary container add-on[0] which also uses containers, but throws them away after being used (like reference counting).
These two tools have seriously improved my ability to both develop and test applications without the hassle of logging out and logging in all the time or needing any tricks when needing multiple clean browsing sessions.
A few more usecases that I've added to my workflow since discovering container tabs:
* Work/personal separation
* Multiple AWS accounts
Also, I am very impressed with how well they're integrated into Firefox. For example, opening a link in a new tab will preserve the container. CMD+Shift+T will restore a recently closed tab and remember its original container. I really like the color coding too.
Use a different Firefox profile for work/personal.
Sign-in to personal (while at work) to sync bookmarks if firewall allows. Depending on whether you trust your employer you could sync further personal settings.
Don't sign-in to work profile and no work bookmarks or settings/logins get shared.
Don't get me wrong: multi-account containers are a blessing for those rare days when you absolutely have to log-in to facebook.
Containers actually still are integrated in the standard installation of Firefox and can be used even without an addon. You just need to turn them on in about:config:
privacy.userContext.enabled to true
privacy.userContext.ui.enabled to true
privacy.userContext.longPressBehavior to 2
I love using containers with privacy.firstparty.isolate set to true too for extra protection.
This add-on is a GUI to the underlying mechanism. They even say you can choose to use the non-GUI lower level hooks. They think this GUI is a nicer user experience
Sounds like I need to move some of my devtesting back to FF. The ability to open a new session with a fresh disconnected session (so no shared session cookies) is one of the few things I miss from bad-old-IE (as simple as "File|NewSession"). Very useful, as you say, for testing workflows between different users.
Of course you've always been able to setup multiple profiles for FF, but that is setup that I was usually too lazy for given it could be done ad-hoc in IE.
I have to agree with you on temporary containers. I spend most of my time in temporary containers. I trade the annoyance of having cookie popups literally every time I visit a page for not actually having to worry about the impact of those cookies.
I have it configured such that middle-click opens links in new containers, and left-click opens in the current container.
The lists for cookies in uBlock Origin never worked for me, I don't know why. It was the first thing I activated on new uBlock installations, now I don't even care to do it.
Hide the popups with uBlock Origin. You pick the element with an inspector like tool and they are gone forever. Also use Cookie Autodelete to remove any information they attach to your browser.
If you really care about a site, make your choices in the cookie popup and grey/white list it in Cookie Autodelete.
Same! I have three (dev, stg, prd) aws accounts. Without containers, I'd need to log in and out to jump between s3/emr/etc buckets between environments. With firefox containers I can run all three concurrently.
I've opted for profiles. With profiles, it's like getting a completely new browser. You start off with the default about:config, preferences and no extensions.
The way my main FF browser is set up, I have multiple privacy enhancing extensions (including uMatrix), highly modified config, tightening of privacy preferences, WebRTC off, service workers disabled, telemetry disabled, etc and etc... This can create some problems on sites that pour hundreds of millions into tracking, data-collection.
So I have additional profiles that are Amazon-specific, Google-specific. If I facebook'd, I'd have a profile for them too. Each of these domain-based profiles are far more liberal (minimal extensions and such; fewer config tweaks). I even have a profile that's 100% Private Mode (ie, history, cookies... deleted after shutdown) with it's own set of config tweaks and extensions.
I use my privacy-enhanced default FF for most sites w/o issues. I wanted Google and Amazon completely separate while providing them more access to my browser (so that I could enjoy the full web experience without worry that a browser issue would make it easy for them to steal my entire browser usage). So they're free to rummage around, read cookies, access APIs - but they're only getting their own stuff back.
I feel profiles provide a better defense (all settings, cookies, storage in their own subDirectory) and much more flexibility than containers.
Functionality is similar, but containers are a lot easier to manage than profiles in FF for me. Everything is right in the container icon and you don't have to re-login like when setting up profiles. You can create new containers and remove unused ones in a couple of seconds vs profiles which are much slower to manage.
I don't bother with profiles any more, especially since there's a one click option to open all the container tabs in a new window as well.
The huge downside with them is they don't sync across devices. If/When this comes they will be perfect.
Having every new tab open in a temporary container was a bit jarring for me (it closes the new tab right after opening it, then opens it again in a temporary container tab), but what works very well for me is the ability to open specific links in a temporary container using the Trash Panda extension: https://addons.mozilla.org/en-US/firefox/addon/trash-bear/
Seconded. We have several levels of dev/test/production cloud services, including backends on cloud providers etc. It’s great to have one container for each group of services!
Agreed and seconded. I use them mainly for testing and for demo. If I need to switch personas but not have multiple private tabs open it is a game changer.
Thanks for this tip. It will come in super useful during web app penetration tests, being able to have sessions with multiple users open at the same time.
I can forgive the somewhat limited user interface for setting these up that is in the stock add-on, but the lack of automatic syncing of rules to all computers with the same Firefox account is really frustrating to deal with.
Putting in the effort to get them all set up nicely and then having them either blown away (I think this happened once...) or needing to get that over to another computer has made me limit my use to fewer containers than I probably would otherwise use.
That particular bug (having my container setup get blown away) has happened to me several times along with other bugs like not properly restoring tabs in the designated container when you restart FF to apply an update.
Bugs like that would be forgivable if they'd at least provide a way to export/import setups.
There is a plugin that will sync the actual containers, but it doesn't sync your rules you setup to always open site X in your personal container, etc.
Without that, its useless to me. There is a bugzilla [0] for it, and 3 years ago, it was said they were going to look more into it, and nothing really since.. Its frustrating.
Predictably, synchronizing data is complicated, so it's taking a while and we're trying to do it in a way that doesn't destroy any existing data. So we'll be doing some heavy internal testing on it before we release it.
My only complaint (and really this is my biggest gripe with Firefox in general) is that there is no support for syncing containers using your Firefox account. This means every time I set up a new computer I have to reconfigure my containers and for each computer I have to re-associate all the sites I have sandbox with their own containers. This is such a huge pain.
It's also a great issue for me since I have to reconfigure everything.
I don't know how the Firefox account works but the fact that FMAC is an extension and not natively included in Firefox may be explaining why it's not synced ?
Unfortunately, it doesn't sync.
You can copy the text anywhere (e.g. email to yourself!) and use it elsewhere; it's still a much better UX compared to the built-in functionality.
I really really want support for multiple browser profiles in Firefox. Multi-Account Containers are cool, but they don't allow me to change my bookmarks or browser extensions. This is the only thing left Chrome has over Firefox that I honestly care about.
The profile manager (about:profiles) comes so close, but it's just not as elegant as Chrome. Starting Firefox with the profile manager also causes issues when the OS tries to open another Firefox instance.
They have a Firefox sync profile badge now. Just give me the option in that menu to open a new Firefox instance with another profile. And when the OS tries to open a webpage, just use the default profile - or even whatever profile I opened a page with last.
Every time this comes up, everyone always dismisses it by just pointing to about:profile or the launch flags, but in my opinion those are weak excuses.
Chrome made profiles a first class citizen and they're an absolute pleasure to use. I literally use them every day. Firefox having a bunch of buried half baked UI isn't really an answer to that.
I believe Firefox is a better browser overall. Only this (profiles), the terrible bookmark/history experience (wtf is that?), and the developer bar are the remaining weaknesses.
The entire Library, Bookmarks/History/the archaic Downloads popup, all just makes me immensely sad. Meanwhile I keep seeing more badges (Pocket, Screenshots, Lockwise, etc) crap popping up in the browser UX...
To add on to what you're pointing out -- they even cloned Chrome's "profile-icon-in-the-bar" model, but didn't actually give you the ability to switch profiles with it! Instead more places to shove more links that I forgot about - Firefox Monitor and Firefox Send.
The history and bookmark management also has some unfortunate performance issues. I'm fairly certain there's a memory leak or something as well, as deleting several thousand entries at once (say, via 'forget this site' menu options) effectively breaks the browser until restart even when it has finished the operation.
A comment in the bugzilla for this issue[1] seems to suggest that they'd like to rewrite History at the very least. So it's on the priority list somewhere.
"Forget this site" seems to work well for me, but selecting thousands of history items manually and then pressing the delete key will lock firefox up for tens of minutes.
There is definitely something profoundly broken with how history is being handled. Probably more than one thing that's broken, from the sounds of it.
Not only that, but attempting to actually create a lunch shortcut on MacOS or Linux with custom profile is quite an exercise since it's not as intuitive to do as on Windows.
It would also be a great place to advertise the Containers extension for those users for whom profiles are a bit overkill (especially them opening in different windows).
I made a fork of this that gives you some additional control over how links are treated - specifically, you can set it up different rules for what container to open a page in depending on what container it was opened from: https://addons.mozilla.org/en-US/firefox/addon/containers-wi...
The rationale is that you rarely want pages that you open from random Facebook posts or Reddit submissions, or pages that you arrive at by following more links from those, to have access to your Facebook or Reddit login information.
The annoying thing about your extension is that the end-user would need to know about and update the domains they want to keep isolated. It would be great if all these extensions/features were built into the original extension and there were updating isolation lists similar to the uBlock Origin lists (EasyList, Peter Lowe's list, etc.).
I use Temporary Containers (https://addons.mozilla.org/en-US/firefox/addon/temporary-con...) to do this. You can customize how you want links handled when they target different domains. It takes some getting used to as there are a handful of options to understand/customize. Plus you can have customizations where you're replacing the current container with a new one which kills off your back button history. Just need to be aware of the quirks. It's definitely still in the realm of power-user UX.
Perfect! This is the functionality I've been looking for. I already had a container addon for Amazon and Facebook for this which should be unnecessary and with your fork it is.
I'll be trying this— I like Firefox containers a lot, but I dislike how session-oriented they are. You can force a particular site into container X, but every click from there will stay in container X unless another rule forces it to a different containers.
What I want is something more like "jail site X in container X, and open every non-X link in a temporary container / container Y / whatever."
I use containers + Cookie Auto delete [0]. In the HN container, I keep HN cookies. Anything opened from HN will stay in the HN container and non-HN sites get cookies deleted shortly. This reduces some tracking for me, but doesn't do anything for something like an XSS against HN that the GP seems to be referring to.
Nostalgic mode: I created a Firefox extension 11 years ago enabling users to have cookie containers by a tab (even when the Firefox API didn't enable this, it was basically a hack). Submitted the extension to the Firefox extend contest but not even a mention there. You can check an old video [1]
The biggest drawback with Multi-Account containers is that they don't sync with the Firefox Sync. I have an elaborate and carefully crafted set of containers. I even have one for TheGuradian where I am allowing ads but the moment a new machine is added to the workflow all is lost.
For privacy, I use first-party isolation. The effect is that all domains get their own container. In day-to-day use I haven't seen any sites that don't work with it enabled.
I use Temporary Containers all day. Love this addon. This is fantastic not only for privacy/security for everyday use but also great for testing sites while doing development. It becomes really easy to be logged into all the different types of users in a website at the same time and see the interaction.
Agreed. I have mine in automatic mode. My default browsing experience is that most pages have never seen my computer before (at least as far as cookies go), and don't get to set anything that will stick around, unless I manually add them to a named container.
I tried this for awhile. It completely breaks some sites, like Jira iirc. It was completely unusable on my work PC. And broke stuff randomly on my home PC. The biggest problem is that you can't easily add a whitelist to fix it. At least you couldn't back when it first came out.
Are you referring to the multi-container extension? With first-party isolation there's no visual indication of containers. It seems to work on mobile for me (FF Android 68.4.1).
This a really useful extension for working with multiple cloud service accounts (e.g. AWS assumes a global session, GCP theoretically supports multiple logins but it's in the usual Google NOQA zone where many things break) but there's a really important limitation to know about: the container configuration isn't synchronized with your account. This means that if anything reset your Firefox profile (like that bug they had last year) or if you use multiple computers, you'll be spending a lot of time duplicating the configuration:
As of Dec 2019, it looks like some traction will be coming to syncing just Containers and Site Assignments (which I believe would perfectly suffice most basic needs).
I use this less for privacy and more for being able to keep all the different account signins straight. I wish there were support in the bookmark where I can define which bookmark targets which container.
> With #1537, our next release starts to address container-bookmark integration & UX. As @MichaelTunnell points out, it does not solve ALL of the container-bookmark UX requests in this issue, or in #854 #1142 and #1443.
> Container-bookmark UX is a big project, and some of the solutions will require changes in Firefox itself. Any changes here could introduce tricky bugs both in technical integration and in UX flows.
In the meantime, I have been using a hacky work-around that more or less does the core thing that I want: quickly open up a specific bookmark in a specific container. (Actually adding it into the bookmarks and syncing across devices is a pain, but not as painful as not being able to open up bookmarks into specific containers).
Same here. I have a work GitHub account, and a personal GitHub account, and am signed into each in a different container. Saves constant logging out and in, or using different browsers for each.
Easily one of the most useful extensions I've ever used in any browser. My only annoyance with it is that One Tab -- www.one-tab.com -- doesn't remember in which container to re-open saved tabs. I really wish this feature would be implemented in Safari, Edge, and Chrome.
This was long time ago. It does compartmentalize the browsing info but the history is still accessible with other containers. For example, a Shopping container should have its own history. (https://github.com/mozilla/multi-account-containers/issues/4...)
If I wanted to completely separate things like this I would use multiple different profiles. The advantage of the extension is that your history, settings, etc remains constant across the containers.
Profiles are unfortunately much more cumbersome to use than in Chrome.
The UX that container tabs have - being able to use them in the same Windows as other tabs, with accessible open-in options from the tab bar and from various context menus; creating new containers as easily as specifying a name and no more - is the UX that I wish Firefox had for their profiles.
> This would seem to be the basic, beginning use-case from which all other use-cases would follow.
I would never ever want to do that. So, no, it is not the basic, beginning use-case. It is a worthless use case for me. You shouldn't assume that your use cases are the obvious ones.
How do you open new, specific, container tabs with a keystroke then ?
As far as I can tell, the only way to open a specific container tab is to mousey-mouse-mouse to:
File > New Container Tab > Blah
Of course that use-case should be preserved, but it's woefully inefficient ... if you have a profile you do a lot of things under, you'd create a window and then (keystroke) (CMD)-t to get a new tab ...
It's not super-efficient, but it is keyboard accessible: press Ctrl+. to open the Container selection menu, then the down arrow to the Container you want, and Enter to open a new tab in that Container.
You can judge for yourself by typing 'firefox -P -no-remote'. Right there, having to use the terminal , has already made it more clunkier than Chromium's solution. Admittedly, Firefox profiles are clunkier to launch & manage - like a hidden feature that has rebuffed all my attempts to streamline their management, as if by design. This can be remedied by use of desktop shortcuts (You can create separate shortcuts for different profiles) but then you have to also deal with the idiosyncrasies of your Desktop Environment (Gnome in my case :/) .
Once its launched its pretty much like running to separate firefox instances in your system with separate bookmarks, histories, settings, addons - like in Chrome. So it is a lot more heavier than containers as a result. Which is why i think the 2 functionalities shouldn't me unified like people in the comments seem to be asking. Similar to Threads vs processes. We need both.
Either way my point stands. Firefox containers aren't profiles and imo shouldn't replace them. They should make profiles more user-accessible, but both solutions should exist simultaneously. If anything, effective use of containers requires more advanced knowledge & awareness making it more suitaed for advanced users.
Is there any way to run this on mobile Firefox? I've loved this on desktop and installed firefox on my Android tablet but this addon shows as "not available".
I don't think so, I am set up on mobile to use a password safe for account login, then I delete all cookies and state on log out. So when the browser opens, there's usually nothing in it, and then the signing for the site I want to go to is auto filled making login pretty simple, then I quit on close.
Focus is great, but it doesn't handle the use case of having multiple accounts for a site that you don't have to sign in each time to use. Otherwise it's basically a fancy "private browsing" window.
A fantastic feature, but has a really frustrating UX issue still not fixed which is that you can't auto open a 'homepage' site for a new container tab, so say for example you have a container for one specific site, you have to open a new container tab and then open that site using a bookmark or similar.
What you can do is have a certain site auto open in a specific container, that way you can just go to the site from a bookmark, link, the address bar etc and it is just one step, but this breaks when you have more than one account on the same site and want a container for each.
If anyone does know a workaround for this, or knows if there's a fix coming, would be really interested to hear!
* If you disable Multi-Account Containers at ANY TIME, all of your configuration will be gone. So, don't ever disable it. Or just be prepared.
* They don't sync with Firefox Sync.
* I use Alfred and in some of my workflows, when I have URLs that are designed to always open in a particular container, FF just won't open the URL. /shrug
* Always opening URLs depends on the URL. This works great for apps which give you account-specific URLs (e.g. Harvest, Jira, other services...) but doesn't work at all for stuff like Gmail or Drive. I wish there was a way to get FF to ask you how you want to open a URL like that.
I would happily donate a thousand dollars towards seeing MAC integrated as a first-rate feature. As-is, I have a massive love-hate relationship with it.
1. I'm horrified using Chrome these days. Browsing to a random site and having my Google account avatar pop up and offer to log me in is really unacceptable. So I fundamentally love what MAC provides. (Though some of this is also Firefox's aggressive cookie options.)
2. It's ridiculously buggy. "Reopen in Container Tab" often reloads in the exact same container. Trust me, I've checked the various bits of configuration that control defaulting certain domains to certain containers, there are just times that it does the wrong thing.
3. The config is hard to backup? I gave up last time I tried. It's a lot of work to get all of the domains setup to open in certain containers, establish the naming/coloring conventions so that it's not a mental burden.... and then have to lose it when I'm inevitably told that somehow Linux performance will be magically better if I make a new profile.
Example usages: multiple "personas". I have a Google Suite account and domain for certain things. I don't have issues switching between Google accounts because to Google, I'm only ever logged into one at a time. Dev/Test purposes.
I recently started using the multi-account container addon. And I love it. Just before I also started using Mozilla's Facebook container[1] and it works as intended as well.
I know supercookies and other fingerprinting means I am probably being tracked still, but at least I am minimising it without going full time incognito.
Previously I was using Profiles to separate personal, work and clients, and though about:profiles help switching quicker it was still messy, and confusing which profile a link would open in etc.
Now I can separate Facebook, Google products and Amazon into their own containers. I can keep various client browsing separate from my personal, I can keep more suspect websites in its own container, finance, infrastructure etc. Love it.
I use this and for the most part it works just fine. The other day I ran into a problem where it got into this loop and I ended up making Chrome as my default browser just to get around this issue.
The issue is when you've an app that needs Google authentication and it opens the browser. To be more specific, I was trying to log in on Postman using the web authentication option. It opened my default browser (Firefox) just fine but it opened my other container (Work) which is not associated with my Google login. When i asked it to re-open the page in the other container (Personal), it lost all the redirect information and wouldn't let me continue back to Postman. I swear I had this same issue with another app but can't recall its name.
I suppose i could workaround this issue by having my personal container handle all the postman links but it seems like too many steps to get one thing.
Does it work with Firefox Sync yet? That's the only thing stopping me from using containers - I've got multiple machines I would need to sync containers between. Last time I checked (admittedly a few years ago) it didn't and it seemed unlikely to be added any time soon.
I combine containers with running multiple copies of Firefox under different profiles. I've been using multiple profiles for years, and I think it still offers some advantages even with container support. The big one is that one instance of the browser can crash or be restarted without any impact to the others. It also distributes resource consumption over multiple independent processes, though I'm sure there's some overhead in this approach. Finally, it allows slightly different settings for each profile depending on need. I manage common settings with a user.js file.
One profile is for logging into various services I regularly use, one is dedicated to day-to-day surfing, one is for local development (there are no addons in this one), one is specifically for webmail, and one is specifically for Trello. Containers are most useful with the first two profiles...especially the first, so that the various services have some level of isolation.
I have a container for each of my prod AWS Accounts. I do a lot of infra work, so being able to compare different accounts, and have them all signed in at once is nice.
Or if you're a consultant working on mobile apps for different clients, having separate containers for each client allows you to be in all of the client's Google Play Console at the same time in one browser.
(Or in multiple accounts/logins of Twitter, Facebook, Gmail, Outlook, etc...)
Pretty much those, plus WhatsApp (distinct from Facebook), because I don't use Facebook, except as being tracked across the Web, but I'm using WhatsApp Desktop extensively, and wanted that separated.
I might add separate containers for separate Twitter accounts, because the multiple account UI on Twitter's web site is atrocious, IMO. I'm constantly "in the wrong account".
At work I set up a container for all the domains and servers my company uses versus everything else.
I have containers for: Banking, Google (and the few places where I use Google as my SSO provider), Work, and then a general "I'm Signed In" container.
I also use the Temporary Containers extension for added privacy, though it's... still pretty rough around the edges, particularly when dealing with sites that use SSO (since kicking out to an OAuth provider causes a new temporary container to be opened, which then messes up the auth flow).
I have it similarly, except that I have Google work and Google private separated.
Unfortunately at work we are using a lot of OAuth, so I am supposed to use AWS and others with Google authentication. Which means that I cannot isolate them anymore. At the moment I still use my old AWS IAM account, but the plan is to remove the credentials. On other services I have never had any separate credentials :(
Personal, Banking, Work Place 1, Work Place 2, Junk (for social media) and then a couple others as spares
My key use of this is to manage multiple login sessions to the same site. Having a bunch of spare containers lets me do this in the same browser window. And I don't have to worry about closing them (compared to using private browsing)
Firefox Multi-Account Containers are impossible to go back from once you get used to them. Add in Conex (https://addons.mozilla.org/en-US/firefox/addon/conex/) and you have really great tab group switching WITH containerization / "firewall" between containers.
You can't get anywhere near this with Chrome as far as I'm aware.
Far inferior IMO. Containers are incredibly lightweight compared to opening a separate profile. I would say Firefox profiles are more cumbersome to use than chromes..
I like profiles, use them all day long, but I wish there was a container-like way to isolate sub-profile tabs. Similar to the "facebook container" or being able to have multiple aws account sub-containers in my "work" profile. It's something I wish I could do.
Nice. Now my wife and I can both stay logged in to our email. I've wanted this feature for 15 years. Now, bring multi row tabs back and FF will be awesome again.
Have you considered just creating multiple windows/mac accounts? Since you can switch without having to log off, it's really convenient. I understand partners sharing accounts and such but it's really just a better workflow/experience IMHO.
I have been using this for a while now, it's pretty good, but I always had trouble separating Gmail and Google search. It's necessary to add accounts.google.com and mail.google.com
I think I can't isolate Google search to ours own container.
I'm also using strict setting and cookies are cleared when Firefox is closed, and Gmail and accounts domain are white listed.
Do you want to be logged in while using Google search? I don't. So I have 2 Google containers (work + private) where I am logged in for Gmail, Drive etc. But search, maps, etc. I do in a 3rd container. Yeah, you cannot blindly follow all links, but that doesn't bother me too much.
I agree, this feature is awesome for development. One of the logging platforms we use (PaperTrail) uses a single cookie for connecting to their platform. This in turn, makes it a complete pain if I want to view logs for a dev/staging instance because it logs me out of our live logs.
Multi-Account Containers completely fixed this for me.
An alternative is to use firejail. If you want temp profiles you can write a script that:
- copies a good initial profile to /dev/shm
- launches Firefox in firejail with —private that points to the dir
- delete the dir
If you want the containers to stick around you can avoid /dev/shm and keep the dirs around instead.
These are pretty good, but the Chrome implementation is better. Specific complaints:
- can't tie a bookmark to a container.
- too many clicks to open a new tab in a container (in Chrome the whole window stays tied to the container, not just the tab)
- bookmarks and history aren't container-scoped.
Are you referring to Chrome's profiles? Because Firefox's counterpart to that is Firefox profiles, not containers. Firefox profiles are clunkier to launch & use though (like a hidden feature that has rebuffed all my attempts to streamline their management, as if by design). Type 'firefox -P -no-remote' to start with firefox profiles.
IMO containers and profile functionalities shouldn't be mixed. Containers are a lightweight version of Profiles. Running 2 profiles is essentially running 2 separate browsers running with separate histories, add-ons, bookmarks, settings. A bit like threads vs processes.
The use case for containers is totally different from the use case for profiles. The whole point of this feature is that you can have all of the cookies and persistent storage of a tab or set of tabs sandboxed, without affecting your actual browser history or bookmarks.
If you want that, use profiles.
>too many clicks to open a new tab in a container
The configuration for this is really simple. There's even extensions like "temporary container tab" that will give you a fresh container with one click.
I'm not sure what you're getting at regarding profiles. Chrome "personas" seem to be much like Firefox containers, but somewhat easier to use. Don't Firefox profiles require restarting the browser?
I guess I am not smart enough to figure out the simple configuration you mention.
I understand that, but why is it done that way? It's extra work to install it, and the fact that it's an extension probably means that it's not tested as well as normal browser UI. I really hate using extensions because I like to keep my software plain vanilla as possible to avoid strange bugs.
Because it's not the sort of feature that 90% of Firefox users would care much about. If you aren't aware of what it is and managed to accidentally activate it, you'd probably get really confused why you had to keep logging back into facebook.
In addition, I use the temporary container add-on[0] which also uses containers, but throws them away after being used (like reference counting).
These two tools have seriously improved my ability to both develop and test applications without the hassle of logging out and logging in all the time or needing any tricks when needing multiple clean browsing sessions.
[0]: https://addons.mozilla.org/en-US/firefox/addon/temporary-con...