Let's set aside your idea for aggregating federated content - it's pretty close to what the fediverse does, but it doesn't explain why the individual fediverse

Let's set aside your idea for aggregating federated content - it's pretty close to what the fediverse does, but it doesn't explain why the individual fediverse instances themselves need to be moderated. You're looking at this problem as if content just happens, like it's a vast jungle just growing up all around us and we only have to just pluck the best stuff. But what induces people to post, or contribute, or write anything at all? A community has to exist that will appreciate it. This community will only grow through shared norms. Even if it's a shared norm that we're all here to just post nice cat pictures. So leadership and moderation is essential to create the audience, the aesthetic, the norms - everything that makes the community a rewarding place! If you don't have that you just have a site with random content and no audience, so there's no reason for anyone to post anything.