It takes blog posts to discover these because Mastodon micro communities aren't discoverable and no one knows which ones to sign up for. Mastodon has no long term potential. We're still waiting for the Twitter replacement.
Maybe the Nostr protocol and all its implementations (that do talk with each other) are the true replacement for Twitter? Check out some trending people/topics on Nostr here: https://nostr.band/
Federation means we have numerous copies of every single post ever shared floating around somewhere, that's a massive waste of resources IMO. Similarly, the amount of network traffic grows exponentially as the number of full nodes grows and again wastes a ton of resources. Those kinds of issues could be mitigated by limiting the number of full nodes on the network, but then you are driving towards a centralized system again.
Federation works really well when the different groups are infrequently interacting. Sure there could be a mechanism to jump into another circle, but if federation means multiple servers needing to know the entire state of the world the scaling and coordination problems just don't seem worth it.