One thing that I hate.
I don't remember having ever used Facebook to login into Quora. Yeah, you might say I did, but still I find it treacherously insane that they do this kind of linking with my information.

Don't mind the stretched image thoufh

That's why I don't login with facebook or anything else, it's impossible to predict and control how they are using it.

At least Quora doesn't pretend to be anonymous like a certain app which only allows login via facebook or the phone number...