Community managers must learn to never build a community on someone else's platform.
Also, what real choices of owned plattforms besides old school forums are there?
And you might be impressed how far forums have come. Open source Discourse forum now has built-in Discord like voice and video chat, along with real time text posts. (It also powers some extremely large communities with millions of users.)
ActivityPub, AT Protocol, Nostr, to name a few.
Bully on me for expecting narcissists to grow a spine.