They do sometimes; but they also comply with takedown notices. Thing is, they all mirror each other's data and are located globally. Take one down, 2 more pop up outside your jurisdiction; and files that get taken down are only taken from one provider at a time, while others pick up the slack. It's an endless game of wack-a-mole that's essentially a waste of time.

This is why it's somewhat important to have more than one provider in seprate jurisdictions but not absolutely critical. You can move from one to another pretty seamlessly.