20 years ago, the audio software industry could have decided to support Linux. Some notable players in the industry tried to convince others to do this (e.g. Waves). It didn't work.
Plugin makers, DAW makers all refused to go down that path, despite the possibility of liberating their highly complex, deeply technical products from the whims of Redmond and Cupertino.
At that time, Linux already had better latency than OS X or Windows. It would have provided access to faster, bigger systems than anything you could run OS X or Windows on, and access to ARM "early" too. The industry could have actually convinced people that they need specialized computers, not off-the-shelf laptops and desktops to do this stuff (still largely true). But more or less nobody wanted to play.
And now, in 2020/2021, just as when the PPC->Intel shift happened under Jobs, because Apple tells them all to dance, they will.
It's sort of pathetic, even if all "understandable" from various points of view.
My experience with linux audio as a casual user (hobbyist composer and arranger) was awful. This was about two years ago -- I remember trying to install Jack, completely screwing up my audio configuration, and then spending days mucking around trying to get Pulse Audio working again at all. I never could get my sound card working, and had to nuke my Fedora installation and reinstall. It was a nightmare. (This was around three years ago, on Fedora 25).
While I don't doubt that Linux can be great for audio, if the configuration befuddled someone with a CS degree so badly, I think most ordinary musicians don't stand a chance.
N.B. Compare to something like Soundflower on Mac at that time, and it's no contest -- almost foolproof to set up.
CS degrees are generally not useful with system configuration, and they demonstrably do not cover the concepts associated with audio on computers.
I know dozens of people who've had experiences isomorphic to yours on OS X/macOS, so the truthfulness of this anecdote isn't particularly useful in establishing anything.
But yes, as a casual user who doesn't understand or want to understand the design decisions that led to the current state of audio on a typical Linux machine, macOS will provide a much smoother experience.
I wrote JACK. I know the guys who wrote SoundFlower. I asked them why they wrote SoundFlower when JACK already existed. They said it was because 90% of their user base never wanted 90% of what JACK made possible, so they cooked up a really simple version. "But it barely does anything!" I insisted, grumpily. "Precisely", they said.
If you don't understand the engineering mindset that says that you probably shouldn't do this, then certainly, macOS will look like a much better idea (along with SoundFlower).
That will likely remain true until you run into a situation involving one of the many things that JACK makes possible (note however that I generally advise most new/casual users against using JACK these days, not because it is broken but because as your comment demonstrates, it doesn't make sense to the mindset/workflow that they bring to the table).
I don't doubt that you can do almost anything on Linux if you want, but "easier to get good results with" is a super important consideration that I feel my more dedicated Linux-using friends and acquaintances sometimes undervalue. They'd be horrified at the idea of paying for Rogue Amoeba's Loopback (let alone for a Mac to run it on, of course), but the flip side is that it's a lot easier to do pretty sophisticated audio routing with something like that.
It's an interesting point though.. even if linux can bring you the best but requires 'too much' work for the average audio engineer it's gonna flop I assume. You need balance to survive.
As a plugin vendor supporting Linux: I think the problem might not be technical but is instead all about the UX.
Regardless, it's been great supporting Linux as it appear 5% to 20% of our userbase are now Linux users (macOS 30%).
On Windows or macOS a dictatorship constrain the Audio API to be X and the Graphics API to be Y.
On Linux, as a user I can choose ALSA, JACK, PulseAudio and while I'm sure there is a better option, why is the user asked to make this choice in the first place? Just choose "the best" for the user.
So Linux software usually doesn't hide stuff to users (liberty?) and this quickly translate to a worse beginner/intermediate experience, having too many choices in audio software is usually something to combat.
And Ardour is the perfect example of this: upon opening it asks several questions to the user in a pop-up, while virtually all other DAWs will reopen the last session. There is a significant divide in terms of UX, and I see a bit of this everywhere I go when booting under Linux.
Thanks for the interesting response. Glad to hear you're supporting Linux with your plugins!
There is no way for a DAW to choose "what is best" for the user. On Windows the same range of choices exists whether or not any particular DAW offers it to them. ASIO? WASAPI? WaveRT? MME? There's a case to be made for each, depending on circumstances. Only macOS really gets this right. The user can also select "auto-start" for the audio/MIDI I/O backend, which will cause them to no longer be asked which to use each time. This is a reasonable choice if they always use the same computer with the same audio interface. It's not so great if those things change quite a bit.
You're absolutely right that the GUI situation is a mess though. There is no standard graphics API on Linux beside X Window, which is totally unsuitable for direct use in any modern development effort. The desktop toolkits (Qt and GTK etc.) are unsuitable because they cannot be easily statically linked into your plugin, which can then lead to version clashes with whatever the host might use (e.g. your plugin uses QtN, the host uses QtM). There is no good solution to this: we always advise plugin authors to avoid desktop toolkits, and if possible use small standalone statically-linkable GUI toolkits designed for the purpose (PUGL, RobTk and a few others). Alas, even JUCE by default tries to link in some version of Qt (it can be turned off, and should be).
On restarting Ardour, it gives the user the choice of a new session or selecting from a list of recent sessions. I've never heard of anyone suggesting that the correct behavior is "open the last session" and this would differ from the behavior of numerous other creatives applications too. If you start up Inkscape or GIMP (or its derivatives) they will not open the most recent file/project automatically.
> having too many choices in audio software is usually something to combat.
Plugin makers, DAW makers all refused to go down that path, despite the possibility of liberating their highly complex, deeply technical products from the whims of Redmond and Cupertino.
At that time, Linux already had better latency than OS X or Windows. It would have provided access to faster, bigger systems than anything you could run OS X or Windows on, and access to ARM "early" too. The industry could have actually convinced people that they need specialized computers, not off-the-shelf laptops and desktops to do this stuff (still largely true). But more or less nobody wanted to play.
And now, in 2020/2021, just as when the PPC->Intel shift happened under Jobs, because Apple tells them all to dance, they will.
It's sort of pathetic, even if all "understandable" from various points of view.