> Interaction contracts into small meshes of trusted, verifiably human participants to keep the tides of spamslop at bay

This is already happening and you don't have to look far to find it.

Personally HN is the only site I browse and comment on anymore (and I'm on here less than I once was). The vast, vast majority of my time online is spent in walled off Discords and Matrix chats where I know everyone and where there's a high bar to add new people. I have no real interest in open communities anymore.