True. It just depends on the barrier of entry.

If you're using TOR to troll some video game nemesis or order drugs off silk road, odds are nobody is going to care enough to pursue you.

If you're a terrorist and use it to tell people you're going to nuke 8 big cities and the pentagon tomorrow (and of course it's a threat they take seriously), you can bet the feds are going to probably figure out a way to identify you pretty quickly.