I love this because I knew exactly what he was talking about the minute I heard it. Fan’s of geek fantasy movie “The Princess Bride” should recognize the reference as well – that no matter how great the legend, there is no one “Dread Pirate Roberts.” It is a role, filled by rotating players.
One answer to the authorship question does suggest exactly this, that “Shakespeare” was more a brand than a person, and numerous playwrights took turns (for whatever reason) writing under that name.
I don’t know that it has any more merit than any of the other theories, but it does seem the most flexible. When the facts don’t fit for play X by playwright Y, just insert a different playwright!