That's still pretty bad advise in the face of reality. The general public doesn't understand OpenID. It was designed for technically-well-versed bloggers and homepage owners. It's way too complex for Grandma. It's a non-solution.

OpenID is not a login protocol. It's a homepage / URL verification scheme. Bending it for something else might make technical sense, but it's hardly userfriendly. URLs are not designed as user identifiers, and the builtin address bar magic doesn't help it. It's working on Stackoverflow because people have a lot more technical competence. For anybody else, only user@something accounts are viable. But it's way too late for OpenID3 to fix that; nevermind the anti-privacy features built into the protocol.