First of all, a forum is a social network. A primitive one, sure, with origins before "social network" had really entered our lexicon, but a social network none

First of all, a forum is a social network. A primitive one, sure, with origins before "social network" had really entered our lexicon, but a social network nonetheless. The ability of people in a federated social network to create arbitrary, independent instances with rules tailored for particular discussion topics is a feature, not a bug. If you don't like that... well, don't go on topic-specific Mastodon servers I guess. Are you advocating for Mastodon to have SSO? If so, I can get on board with that. Are you advocating for a cap on the number of members of a particular instance? Mastodon can already do that - all you have to do is not approve new accounts. Of course, the inherent problem with that is that activity in member-capped servers will gradually die out, and now you need way more admins... your idea, not mine.