I agree with three_jump. Plus, being fast (and thus winning races, winning points and progressing through the ranks) doesn't necessarily equal having racing skills, and vice versa. There's plenty of people who are blazingly fast but don't know how to properly race in a close battle with other drivers.
I'm not very fast, I'm usually somewhere middle pack, but I am consistent, aware of my surroundings and can race side by side and bumper to bumper with another driver for laps on end (provided the other driver knows how to race closely as well). It usually takes me quite a bit of time to get enough points to get to the next rank, and I can't be arsed to do that.
That being said, though, z-ro does have a point; there are lots of "normal" servers around, it's just that most of them are empty and the populated ones just happen to use some kind of ranking system. Not much you can do about that.
Also, I'm really not too fussed about this because like I said, for the past 2 years or so I have almost exclusively raced on the dMr server so this problem doesn't affect me, but I can see how it can give a wrong impression to a newcomer.