The MPAA aren't stupid. They're greedy. It's not run by Harvard graduates so they can do silly things like attempt to actually wipe out piracy, the prime reason for anything is so they can make more money.
Of course they fully know their attempts at ending piracy are futile, that is not the aim here. The aim is simply to
leech money. Ending piracy isn't magically going to pump money into the economy so people spend more on movies, that's just daft.
Who will they sue if piracy ended tomorrow? That's right, no one, therefore they don't actually want piracy to end. Of course they are also aware that for every 1 site they shut down, 3+ more crop up; if you think that's some secret underground knowledge the MPAA doesn't know about, you're very naive. They absolutely love the fact more are cropping up for every one shut down, otherwise they wouldn't shut them down in the first place - very simple cause & effect logic.
Also, should mention the mainstream headlines these lawsuit escapades generate. Last time I read a mainstream news story about a pirate site getting blocked/shut down I found several new torrent sites I'd never even heard about