The goal of federation is explicitly NOT decentralised content.
It DOES store content it in a decentralized way.
It DOES allow interaction in a decentralized way.
It DOES NOT decentralize control of the content. It can't. It shouldn't.
The admin of an instance, can control all content on it.
The top mod of a community, can control all content on it, across instances.
You are in control of your own content, across instances.
In a system that is truly peer to peer, truly decentralized, you could not edit. You could not delete. You couldn't even reliably take down content that breaks the law.
The point is not that no-one should be in control of anything. Quite the opposite. The point is that no one entity should be in control of everything.
In this, federation is completely different from other systems.