So I'd basically have to hope posts from people I'm interested in filter their way onto the server I start on and sort of crawl around until I find communities

So I'd basically have to hope posts from people I'm interested in filter their way onto the server I start on and sort of crawl around until I find communities I'd actually want to participate in? How does the cross pollination between servers work? I haven't seen a good description on it besides that you can DM people across servers. The content is also structured in a twitter microblog + replies style. So I'm seeing basically private forums of old, but twitter format and some weird soft discovery thing. Overall I like the idea of federation, but mastadon seems half baked. I signed up and I'll get it a try for a week or so though.