>How about using forums again,

Not sure what forums software you're thinking of but vBulletin, phpBB, Discourse don't have the extra features the author is looking for.

He wrote: >Many of these make heavy use of Discord's voice channels, video chat, and screensharing. These servers have a hard requirement for adequate moderation tools for dealing with any bad actor willing to join the community. [...] Decent Mobile Experience [...]

A lot of admins shut down the forums software and moved to Discord because it didn't have the modern features they wanted. So to migrate off of Discord requires an alternative that duplicates most of what makes Discord valuable. That's what the topic admins wish for but the current options don't give them that.

>otherwise irc, bluesky, matrix

Author analyzed the IRC and Matrix deficiencies as not being acceptable.