Lets put it this way. Most drugs climbers use hinder rather than enhance performance. The level playing field exists and those who excel do so because they have natural talent.
The same is not true of the Olympics, or the Tour de France. Doping is widespread in these sports. The playing field is not level. In order for Lance to be beating his opponents through his postulated inherent ability, he must first be doped up to their level, in order to counteract the benefits they gain from being doped.