[natrius]

I think this reverse Yelp you describe is coming soon, partially because I plan on helping to build it. A "trade embargo" can be an effective punishment of last resort for any sort of bad behavior, from crime to a failure to contribute to a particular public good. You could use it to take collective action where the state won't, or maybe eventually to replace the state without needing to use force.

You could store people's cryptographic identities and reputations on a global computer than anyone can access, but with rules that no one can break. That now exists, and it's called Ethereum.

An embargo is a pretty harsh punishment, though. In practice, you'd probably only use it when someone fails to provide some lesser form of restitution.