It disregards the benefits of a distributed platform. Imagine if the admins went rouge, or the server data was irreversibly lost, suddenly all that content would be gone or under the authoritarian rule of the admins. Bit dramatic but you get the point.

If the majority of content is on there, we've quite literally taken a decentralised system and centralised it lol

Personally, I've found Reddit now Lemmy to be better than other social media because the focus is on the content rather than the poster.

Instead of following individual people, you follow topics. This encourages more quality content rather than personal clout

Standalone book: The Neverending Story

Book series: It's a hard choice between The Hitchhiker's Guide by Douglas Adams and His Dark Materials by Philip Pullman

Big part of the concept of a fediverse is the decentralisation. It would be beneficial I think for more people to register on smaller-medium sized instances to help reduce the load on the large few