Facebook login required? Forgitaboutit. I've never had a facebook account and never will (sure, I know you maybe can use another service...but just it isn't worth my time).
Quora was started by ex-Facebook CTO / VP Eng, who previously lead "Facebook Platform", i.e. the login requirement now seen at Quora. However, most of the world moved on.
http://pando.com/2013/07/23/move-fast-break-things-the-sad-s...
http://www.crunchbase.com/person/adam-d-angelo