What Wave said, basically.
I was just thinking of it because I realized that if someone really wanted to, they could just sit there and play, say, Tery and Fuelbi (sorry guys, I just know you both proclaim to be really bad battlers a lot, so you're the examples) a lot and sit higher on the rankings than some others who were facing players that tend to be much better. It would also maybe give us a way of panning out ties, if it were needed.
I do realize it's not entirely needed though, as someone who does that could easily be taken on by someone who's good and get their ranking knocked down a notch or two, but it still might help some.