Really? Because I'm pretty sure myself and many others caught it when the T-echo Chamber was trying to sell us on this new message board system that was going to make a lot of money and change the game.
Quora was an online community that happened to be "cool", so it attracted intelligent people which made the content fantastic. But nothing they were doing, in my opinion, was especially original. And as has been pointed out, if you try to scale up an online community, you deal with more and more noise. Predictably, that happened.
I apologize for the past tense; I realize Quora still exists, and nothing I or the author says has any real bearing on where it goes from here, or whether or not it is successful in the future. But I do know that I've gone from using it occasionally to using it never.