There are communities still out there, but there seems to be no modern forum software? They have either been around forever or, if a bit newer, do nothing without mbs of JS.
Now that activitypub is here, there seem to be half a dozen reddit clones in development. Microblogging and social media are also everywhere, but what about forums? What about topic-centric, lasting conversations instead of hot-topic and people-centric chats with no history?
Discourse, Flarum, Talkyard (which I'm developing).
GitHub's new Discussions feature?
Lemmy? https://github.com/LemmyNet/lemmy, "Building a federated alternative to reddit in rust" (how does it matter that it's a reddit alternative? it can still be topic-centric etc?)
Forums require a lot moderation and maintenance. If you don't keep the software up to date they're easy pickings for hackers. Without active moderation they're quickly overrun with spam.
For most people forums end up expensive pains in the ass. In terms of ActivityPub, the lasting conversation topic-centric nature of old school forums doesn't really fit in the model of pushing new activity. A hot-topic Reddit clone fits that model much better.
Discourse is pretty modern.
(I run Remarkbox and I'm trying to find product market fit)