There was discussion earlier in the thread talking about a TCF-based multiplayer server that has weekly times for progression bosses, but the main issues at that point become server hosting and setting aside a time that works weekly for progression to occur.
It becomes much easier to organize if players aren't worried about being present for specific bosses, but ways you organize progression for cases like randomly spawning bosses become a little awkward. It's entirely plausible that you'd have to lump Wall of Flesh, Demon Altars, and all the Mechs into one day just so random spawns don't hassle players that are on the server just trying to build.
Not worrying too much about progression and just treating it as a social space would be a possibility as well, at which point there'd just be a pre-hardmode and hardmode divide.
I do think it'd be nice for there to just be a casual dedicated server for the forum community, but that's its own discussion.