I hope they enjoy their little game of self-righteous wack-a-mole, because I've little doubt these sites are popping up at least as fast as they're being shut down. Where there is demand...
And the only way to actually put a stop to this sort of thing would be the end of the free internet.
The usefullness of their activities is they are gradually getting rid of the easiest form of piracy. It is so easy to pirate via HTTP. When you make it unviable to profit via HTTP downloads, the bad guys will move to torrents. You can then sue the uploaders. Or get the torrent site shut down. Or cripple their ability to accept donation or profit from ad networks.
Whatever can be done to make it harder for Joe Public to pirate and easier to whip out their credit card, the better. You're average surfer is not going to get into FTP sites, newsgroups or use Frostwire to download a 500mb porn movie.
"they are gradually getting rid of the easiest form of piracy"
See, I'm not convinced they are. Do you really think someone who's raking in "as much as $300,000 per month through Paypal alone" is going to give up just because one site got shut down? The operator need only move to a new domain, a new bank account, maybe drop in some new clip-art and tweak the CSS, and they're off again. Not much effort, considering the pay-out involved.
I wouldn't be surprised if many file-locker operators consider the occasional site getting shut down to be an expected cost of doing business. They might even run multiple sites at once to smooth out these bumps in their income stream.
So, sure, this group's marginally increasing the cost of doing business as a file locker, and so slightly reducing the size of the industry. But it's not going have a meaningful impact -- at least until people start going to prison for wilfully hosting illegal material.
One pornographer, going by the username "AdultKing", is leading a campaign on closing file lockers that profit from illegal uploads by incentivising with affiliate programs.
He is systematically contacting the payment processors for these websites and getting their accounts closed due to the child pornography, bestiality and copyrighted content found on their servers.
And the only way to actually put a stop to this sort of thing would be the end of the free internet.