The legality gives people power to knock on the doors of ISPs, who can (and often do) know everything. Even without that, authorities can (and occasionally do) run honeypots after they find and disband the main site operators.
There is no technical solution to the anti-piracy war, it's entirely a legal problem.
I suppose I'm wondering about the realistic ability to detect and ability to prosecute. I'm not really concerned with legality for legality's sake.