Today I got a support email from someone asking why they needed to establish a password in order to post questions. My first thought was that they were asking about some other site since we delegate authentication to whichever OpenID service the user prefers. But then I did some poking around with an incognito window and I think I understand what happened:
Since the Stack Exchange OpenID option is expanded by default in this tab, it looks like you're going to need to pick a password to signup. If you pick Google or Facebook, that's not at all true. (Well, you need to log into one of those services with a password, but presumably you already have one.) Meanwhile, the "Log in" tab does not expand the Stack Exchange option by default:
Finally, when you want to add a login credential, the Stack Exchange box is expanded again:
(This was confusing to at least one user who thought entering an email and password would have created the account for them.)
I'm not saying this is right or wrong, I just don't understand the reason for it. Why is the Stack Exchange option more prominent for people signing up? Aren't we just confusing our sign up process by making it seem like a password is required?