Two factor auth protects you against someone using your account. Have we had any issues with that?
It does not protect against people signing up for multiple accounts. Unless you were actually planning to send out hardware 2FA tokens to each actual contributor, but I'm pretty sure you didn't mean that?
And as a sidenote, it also doesn't support our version of mediawiki -- but that's only a problem if we actually think it would bring any benefit.
