It works with torrents fine as I said. Or you are talking about P2P indexing? I think this can be solved. And I said that it can be used together with relays. 
The issue with "it works well enough" for me is that in case of an attack, relays can be more easily blocked before there is a ready solution. I personally won't be working on this, so i am not criticizing anyone, but in my personal life I am always proactive instead of reactive.

BallLightning

nostr

Making nostr P2P

P2p is gold but if we're talking about socialmedia-like protocols, I don't think that it would work as espected.
A social platform, being it a protocol or a closed garden, has the goal to solve the issue of content discovery and user discovery. In Nostr, that is somehow solved by the fact that users push content to relays, thus relays can provide content discovery even for users out of each other network of connections.

In P2p you cannot achieve it in any meaningful way, because content is simply pushed to clients directly from other clients. That's a good feature for messaging platforms, not social media.