To answer your question from the nest, aggressive community action.
In a world with no police, you and your community become the police.
On a platform or protocol without content mods and no government legislation, the users become more responsible for making bad actors feel unwelcome.
I do think that it will eventually break down to smaller tribes when things are more decentralized. That’s easier to manage. nostr:note1d4k83u58aw3utyxk0tcxlxmzmd8ge2hypwfpyrt2a3kdsd7gyrjqr44gkv