[thaumasiotes]

> the Ming policy was never 100% effective and mostly just resulted in a lot of smuggling and piracy

I don't think this can really be a complete description of the situation. You can't stop smuggling as a phenomenon, because you can't oversee everything that happens everywhere. So, as much as you might wish it would, the law doesn't really apply to random smugglers.

But by the time you're one of the 100 richest men in China, the law certainly does apply to you. A ban on trade that's "less than 100% effective" is more than enough to stop someone from doing so much trade that they become personally more powerful than the court, as long as "less than 100%" still means "more than 0%".

[bobthepanda]

Haijin wasn't really meant to stop people from becoming more powerful than the court. It was supposed to starve out Japanese pirates.

In reality, the people who were trading mostly continued to do so, becoming pirates and smugglers themselves in the process, and Ming China simultaneously lost a bunch of tax revenue from trade as well as tying up a huge part of the labor force in enforcing a sea ban.

The Qing policy was more successful but also required all property destroyed within 30 miles of the coast or face the death penalty, which is extreme to say the least.