Here's how to make Mastodon better for communities from Twitter:
- Add ability to restrict replies to followers or close them
- Add ability to quote posts in order to provide community-specific context
- Add an optional algorithmic timeline that aggregates popular posts from people you follow and related posts (right now people miss a lot of posts, something bad for communities)
I don't know if the project maintainers _want_ it to be good for communities, but these are the missing features.