Earlier quoted context omitted.
Both ZeroNet and Freenet have decentralized forums. Freenet's forum is called FMS. They have decentralized microblogging too - ZeroMe on ZeroNet and Sone on Freenet. This is a post I wrote about ZeroNet's decentralized microblogging: https://bluishcoder.co.nz/2017/10/12/zerome-decentralized-mi...
Moderation is a must, unfortunately. Matters of trust make it difficult to run code on the users' computers, even if NAT and so forth didn't get in the way. I like the vision of decentralized computing, but I'm afraid it'll be at minimum very inefficient, and possibly infeasible.
Freenet's FMS allows moderation using a web of trust. You provide trust to users pseudo-anonymous identities. And you can choose to trust who they trust. Trust scores are computed and any identity below a level will not be seen by your identity.
Freenet's Sone has similar functionality using a web of trust plugin (FMS has its own trust implementation) that can be used by other plugins.