That’s an interesting question. From a ultimatum perspective I’d say having ways to organize post topics into communities would be helpful for enduring social connection. Hashtags help, but an actual group would be better after a certain point. I don’t know enough about search functions to have any suggestions about that.
Realizing I’m so algorithm trained that I don’t know how you operate w/o it. I.e. friend suggestions etc.
Back in the day of Usenet news, it was effectively a group. Each group/channel became its own ecosystem. People surfed across them as like changing channels.
There was generally a weekly automated post of group basics - culture/rules, Admins, faq, how tos etc.