It would be simpler to decentralize and implement webs of trust[1] (that locality would also help community-building / social cohesion).

Secure Scuttlebutt[1] doesn't have a lack of moderation / spam issue and it is completely decentralized and without monetary fees nor proof-of work. Why can't centralized services do better?

[1]: https://ssbc.github.io/scuttlebutt-protocol-guide/#follow-gr...