Whose fault is it that these things happen? In my opinion, much of the blame lies with the unscrupulous exchanges. If they agreed, the stolen funds could be flagged and they would never be cashed out. With a well-connected and regulated system (Yeah.. I don't like it either.. but it's the only solution I can think of), the exchange from crypto to fiat could be blocked at the moment it happens.
As far as I can remember, exchanges have been notified of the btc addresses, but if those crooks used a bitcoin mixer then it is hard to blame exchanges from accepting those btc. So I wouldn't say that exchanges are part of the problem here. I'm not defending those scammers, but they are well sophisticated that it will take blockchain analysis to really track where the coins are going right now. And it will be too late, once they have cash it out.