There's a lot of really bad stuff on Tor. Like, really bad; probably worse than you're imagining. Things that make the old rotten.com stuff look like a child's birthday party. If Tor was actually compromised, the people creating and uploading that stuff would be grabbed quickly. Instead, LEAs have to cooperate globally and run long-con sting operations in order to identify people in order to bust them. Most of the time, they're busting people that use Tor due to social engineering or one kind or another, and the remaining times it's because someone fucked up configuration on a site.