I tried to login with Facebook, and was prompted to make a password anyway. Doesn't this seem to defeat the point of having OAuth sign-in in the first place? I

I tried to login with Facebook, and was prompted to make a password anyway. Doesn't this seem to defeat the point of having OAuth sign-in in the first place? I don't want to remember your password, and you've already got my login tokens, so I shouldn't need to.