> (1) maybe it doesn't need to scale for people to ultimately have a much better experience
Big, heavy doubt. This Twitter debacle has generated ridiculous, crazy amounts of drama and emoting, the likes I haven't seen on the net in ... a while. This kind of emoting and drama stirring only works when the pot is large. A storm in a small teapot really isn't much. It reminds me of the high drama that used to happen on large IRC channels run by teens in the early '00s, where you'd wake up and some portion of the server got muted or banned for some completely opaque but intensely personal reason. (I was one of the teens so I'm not implying like I was much better than the rest of them lol.)
I'm in 20-something small Matrix rooms/spaces and Discord guilds and none of them are nearly this dramatic. The kind of folks that seek engagement on Twitter IMO are in it for the high drama that you can only get on a large social platform. The folks that stay on the Fediverse are looking for something entirely different. I'm hopeful that some folks try the Fediverse and realize they didn't need Twitter at all (not in some sense of Twitter anger, but more that it's good for folks who want to socialize in smaller spaces be aware that it's very possible to do that on the net right now.)
FWIW If you're trying to build a small community and afraid of scaling issues, I still think hopping onto Matrix or Discord (preferably in that order) is a better idea. Synapse might be heavyweight but it's still lighter than running Mastodon, and if your community doesn't want to federate, you can run the much lighter Dendrite (or even lighter Conduit which is a bit more raw.) There's a large ecosystem of clients on all the big platforms for Matrix. Discord being a centralized, closed system has all of these problems solved as well.