Is managing email really an unsolved problem? I mean, every email client has already way too many "organizing thingies": folders, filters, bookmarks, categories, labels, stars, flags, and archives. What value RSS brings alone except from being different and therefore having its separate tab in a client?
No, I don't think there is much fundamental difference. Some RSS readers support inbound emails as a feed source and I get my RSS feeds delivered via email. I think the main reason newsletters are "winning" over RSS right now is that everyone has an email address but not everyone has a feed reader configured. It provides an easy onboarding where you can start getting it in your inbox available on all of your devices and once that becomes annoying you can easily set up filters to organize.
I thought email was dead. I treat email like I treat voice messages, they are just out there waiting to be deleted without ever being read/listened to. Do people actually use email still outside of a work situation?
A federated near-instant messenger, not being controlled by a single corporate entity, designed on top of a well-defined Internet standard, with both commercial and open-source clients existing for every platform?