It's already semi-p2p by the way federation works. I think it would be highly ineffective to make it actually p2p.

Imagine having every user host their own community on an instance. Then you have to federate across other users to have other content in the instance, . But instead of it being 400 instances now, it's 77,000 instances all trying to stay current from various toshiba shitboxes.

Content aggregation is more of a "master list" problem than a computing problem to solve. Which is easier from a central repo.