The difference between Quora and Facebook, is that me and my friends can upload photos of ourselves drunk and post wall posts of us swearing, and Facebook will be always a good product to the entire community despite this.

With Quora, the community isn't tied down to who you are friends with. There are no friend requests. On Quora, everyone is technically your "friend".

So with that said, it is not just enough to allow people to behave as bad as they want on Quora. If that happened, people would leave in disgust. If I was posting racist things on Facebook, only my friends would know and you would still be using Facebook regardless. On Quora it's not like that.