I think the problem raised about login is due to the limited options, either Facebook or Github.
People don't trust websites that quickly ask for their Facebook account. It looks spammy.
I'm all for third-party authentication, I hate creating yet another account. I think the balance is to offer more choices than just Facebook or Github. And I don't like linking my Github to things that are not directly involving my code.
The way StackExchange does is the right way, I believe. Offering more neutral, flexible OAuth providers than only Facebook (and in that case a smaller player like Github).
This is meant as a constructive comment, if anybody ends up at this line thinking I'm just whining.