I see some attraction to having a standardized API for forums to offer as an alternative to web UI's, but I don't like the Lemmy software all that much (it's too much like Reddit, i.e. oriented towards memes and link propagation rather than discussion), and I don't like social media (defined as systems where other people vote on what you see). I prefer traditional text-only discussion that is purely chronologically ordered with no voting or ranking. Also it should be fine to have private forums. There are private subreddits and private youtube channels and there is private email after all.

Anyway I got into another discussion like this a while back, where I gave my .02 on how I thought Lemmy should work (basically all subscriptions, blocking, ranking etc. should be done in client software that is completely separate from the backend, though it could itself be running on a server of its own). I don't feel like rehashing that. But basically, Usenet was great until spam killed it, so I would just fix a few things about it and try to resuscitate it.