A number of us saw the fluorescent block-letter writing on the Wall and GTFO (past tense). I doubt that any of us regret the decision. I had certain topical engagement that I haven't yet replicated with Mastodon, but those topics were not crucial to remaining. There should be very very little that is.
For me, Mastodon was not my first peer-to-peer rodeo: I've formerly used *Diaspora and smaller offshoot P2P social networks. Technically, I suppose my experience extends all the way back to 1980 and using the renegade $TALK program running on a CDC system at a Cal State campus and a pre-Internet WAN that linked all 19 of the campuses together; $TALK allowed students at all of them to converse in realtime in true peer-to-peer fashion....