So if I understand this right, you pick a server and your server account can post on that server and any servers that that server federates with.
So what happens to your account if the server you joined goes down? Yes, you could always create a new account somewhere else, but you lose all your followed communities and post and comment histories as well.
I created a site directory early on to mitigate this issue but it was too much work to manually curate, even with help. Webrings is a nice idea, but I can’t really see moderators send users away to competing, practically identical communities. In my experience they rather just crosspost to their own.
I think my dream solution would be to subscribe to all know i.e. !gaming communities and post to my local gaming community knowing everybody will see my posts because my community is included in the “subscribe to all known !gaming communities” that others have subscribed to.