I can only speak to the topics I followed on another account, but it provided plenty of reading for those topics. Whether it covered all possible posts and whether it works well for all topics, I couldn’t say.
It does kind of rely on people tagging things properly, which people might not do if they’re on a Mastodon instance specific to that topic. But then, they ought to know that those posts wouldn’t Federate well, and indeed, might not want them to.
They either can’t see it or they see it perfectly well and they like what they see.
You may find either or both of these disgusting.
This logic can also be applied to elections.