The "impossibility" of enforcing legislated constraints on thousands of providers point is hand waving. We're all legislated to not harm each other. Throwing the small fraction who do in jail, is sufficient to keep the vast majority away from harming others, and there is also moral alignment.

If 10% of hosts (maybe even less) are penalized, the rest will likely start complying. much like self managed compliance of thousands of companies. A protocol is only as good as the entities that participate in the community using it.