Well, when I log in with Github/Google/Twitter, I don't necessarily need to confer any account access to the website and I almost never do, so I'm not sure that

Well, when I log in with Github/Google/Twitter, I don't necessarily need to confer any account access to the website and I almost never do, so I'm not sure that's the defining factor of 3rd party login. At that point, 3rd party login really is just "we'll contact their servers to authenticate you and then give you a session." One example would be StackOverflow which lets you log in with Google/Github/Facebook but doesn't ask for any permissions on those websites.