Yes, of course, the creator (or copyright holder) can do whatever he wants with licenses. I was talking from the point of view of other people which are not the creators.
It is hard to know if other people do it correctly or not. Anyway, in previous licenses (GPL v1 and v2, and CC-BY-SA before version 4.0) things were a bit different, so maybe the best way to do it was different, who knows... But that does not matter to us, so forget about that.