It's sort of like if I gave you the name of a drug dealer, then I couldn't really be held responsible for engaging in an illegal activity. Of course, in that case you could be tried as an accessory of a crime, but for copy-right law there is not such a stipulation.
They could try to make one and shut all these sites down, but as to how much of a legal case is present for establishing intellectual property in the first place is still very much a debate, and for the time being it doesn't seem likely that new laws will be passed.