It's not really about that at all. It's just a way of trying to rank people irrespective of the weight they fight at. Trivia: Contrary to some popular opinion, the term was not invented for Sugar Ray Robinson - you can even find many examples of it's use news archives (I've seen it used as early as 1917).
The only tripe I have is Broner being in there and although I'm a fan I still don't believe he's earned his place.Manny Pacqaiuo is way too low aswell he was number 1 not to long ago and now he's number 8 on the back of his loss to Marquez. Ring magazine is a joke anyway I'm sure real fans have an idea who should and shouldn't be p4p