The entire reason why there is a thriving global market for manga is that these off-books sites have existed for decades, and have raised a generation that treats manga as core culture. So they're strangling their continued relevance in a blind enforcement frenzy.

The other big problem of publishers acting this way is that if we start buying more manga after this, the message publishers get is that this works, and to do it again and again. They've created an incentive for manga fans to therefore not buy more manga for now. Which is exactly the opposite incentive publishers wish for.