My concern is that communities on Lemmy are fractured by instance. You CAN read or subscribe to communities on any instance, but communities with the same topics (or even the same names!) on different instances are in no way connected. For example, there can be a community called "Books" on every instance, but if you subscribe to one you will NOT see posts in any of the other Books communities on other instances. You'd have to go out, specifically find each one of them, and subscribe to them separately.

Not to mention communities with different names, but that cover the same essential topic. For example, I'm subscribed to the "Literature" community here. It's nice. But it's entirely disconnected from any of the "Books" communities on other instances. I'm not sure how that sort of fracturing could be addressed. I understand that there's a plan to eventually allow "MultiReddit" style aggregating, allowing users to group a number of communities into a single reading group, but that would only apply to what that individual user would read. No one else would have the benefit of seeing all the posts from those communities in a single group unless they individually recreated that collection.

What might work would be to bake in a set of standard all-instance communities which would automatically merge the content from all instances for those topics for all users. But I'm not sure that would work, since not all instances have to federate with all other instances.