That's an argument for implementing both Facebook and native logins. It's not an argument for refusing to implement native logins at all.

twitter accounts are the best near-universal logins. fast to setup, complete anonymity and easy 2 click comment signin.

I agree, but it still comes back to the same problem. Relying on another site membership. What if SiteA uses Twitter to login because they don't want to make people have yet another login account, but I don't have a Twitter account... Great, so now I have to sign up at Twitter to sign up at SiteA... Making me have to have an account at a site I don't want to have an account at, just to have an account at a site I DO want to have an account at, just because Twitter is more popular.