LOLWUT?
First of all yes they are behind a paywall.
Secondly that's circular logic, they have high traffic because Google ranks them high. You don't rank high in G because you got alexa rank. Geezus.
I think you're on the right track here. That's what this is about. It's politics and money.
Google rankings for big sites are manual.
Not at all. There's more to it.
ALSO PINTEREST. 100% spam, images are never on the page they show and it's paywalled.
These big sites have some arrangement with G.
Yeah but that's cloaking and if you do it you get nuked off serps. Showing googlebot one thing and users another yields penalties for little guys. Why not for major spammers like quora?
Sounds like content farming to me? Google penalizes ezinearticles and so many other sites, why not penalize these select few like quora, pinterest and others who massively generate bad content daily?