It's mob rule and it has been basically since I left. - Larry Sanger

Basically, the Left tends to invade open institutions, it's been their modus-operandi for the last hundred years. Basically, invading open institutions and subverting them, dominating them, and freezing out anyone who dissents their views. I can't tell you what the cause of the bias on Wikipedia is, I can only tell you that it's really obvious now. It used to be quite obvious 10 years ago, now it's just embarrassing... Now there is an official view about pretty much everything...

I actually think that the mechanisms just of people acting like jerks and driving off decent people who want a neutral reference, that's enough to explain the bias

Jimmy Wales is right. We did originally adopt the neutrality policy to foster "a culture of thoughtful diplomatic honesty." In other words, the way to keep the peace among a radically diverse set of contributors is not to declare winners and losers. But that is only one reason we adopted the policy. There was another key reason: as I have explained, no one has a right to make up your mind for you, especially in an open, global project.