Prisoner's dilemma is solved and not a dilemma with repeat rounds (aka trust and relationships). Like the real world. This fits well with the fact that cooperation works, and is why civilization exists.

Yet piracy has been around for thousands of years.

The thing is people and countries don’t all benefit equally from buying into the existing system. It’s the same basic reason people continue to run scams and steal stuff on land etc.

So has trade. Piracy isn't a blockade.

Piracy has been used as a form of blockade.