I think you are kind of right. But if you build p2p people will eventually decide that it sucks and create discoverable "peers" that are functionally relays. Its just a question of what you'd rather fight with. Do you want to forever fight with opening permissions on something too restricted or forever try to lock down and filter something too permissive. I think we should try both.

The assumption within our protocol is that the community owner will stay online or delegate somebody to stay online for them. They need to be online to receive publications and respond with challenges if needed to them. That's the price of having an arbitaerry anti-spam functionality for each community. Eventually we would have lots of public RPCs where people can delegate their community hosting while maintaining ownership by owning the .bso name of that community