To say that Mario Kart doesn't require skill is stupid, because obviously there are people who perform well consistently and people who suck. That said, there is a definite ceiling to how good you can be, at which point luck becomes the determining factor. If you know the tracks well and don't play stupidly, you are going to do pretty well most of the time, but to imply that it is all skill and no luck seems kind of strange to me.