And how google allowed it to happen. Even after they said they are opposed to the behavior.
Like other bad Google behavior related to controlling web spam, I reckon this drives more people to see Google ads on these sorts of sites, so they've taken an anti-user position. Same reason much of the "legitimate" web turned up in Google results now looks like a low effort click farm—if the clicks are making Google money, who cares if it's coming from garbage content?
I'm sure they used to do exactly this. Now, not only do they not do this, but they commit the same sin themselves! Recently I was clicking around Google Images looking for some chart data when I found a promising Google Docs link. Alas, "you must sign in to access this document". Get bent, Google.