Is there a plugin that does this? Is it even possible under WordPress? Setting aside that issue of technical feasibility, it seems nonsensical to me that I have to have a local user created -- with access to the dashboard and a user profile, etc. -- just to have someone post a comment by using, say, Twitter as their login.
Is there really no way to have a user authenticate via Twitter, have WordPress use their Twitter handle and profile URL as the comment's name/URL, and then move on, without creating a local user profile?
If the commenter is authenticated, why do I also need to them have a version of that user stored/accessible within WordPress itself? All that matters (to me) is that they are authenticated, just as they will be the *next* time they comment this way.
I don't need the user management headache, and the user doesn't need to have yet another account hanging around on the Internet.
So, is this technically feasible? If so, is there a plugin for it? If not, why not?