Do you think the fact some athletes take EPO also during training in altitude can be a reason for thinking they are right ?
Many years ago, at the time of doping with steroids for the Soviet Block (including URSS, East Germany, Bulgaria, Hungary, Poland and Romania), the Russian Methodologists introduced training with heavy weights, supported by steroids, for jumpers. The best athlete they had in long jump was Valeriy Podluzhny, PB of 8.18 and medal in Moscow Olympics. Podluzhny, like before him Ter Ovanesyan, never used heavy weights in their training. The Russian coaches thought that, with more muscle strength built with weights, Podluzhny could become very much better, but in the next 6 years he never was able to jump more than 8 meters, because gaining strengt lost elasticity and reactivity. In that period, all the athletes of the Soviet Block used to increase their strength with heavy weights, and nobody improved, till when the coach of Emmiyan decided to reduce weights increasing training of speed and plyometric.
In 2004, Yury Borzakovskiy won 800m in Olympics (Athens) after 4 full months of indoor training during winter, and the most part of coaches said "for 800m a full indoor season is very important", without thinking he was 3 months in Moscow with temperature under 20° negative.
In 2008 Wilfred Bungei won, and in 2012 Rudisha. They never had the indoor season before Olympics, and Rudisha never ran one indoor race.
Put in your mind that, like in training, in doping there is FASHION. The majority of athletes follow the training system who produced results for somebody else, and, if not correct, follow the DOPING SYSTEM that has more "audience", because don't have any knowledge about the real effects (does it work ? doesn't work ? if Others do, it's because can produce results, so I can follow the same way). They use exactly your way of thinking, obviously not the most scientific and clever way for understanding if the solution is good or not.
When I say that people like you, overrating the effects of doping on the performances, are the FIRST TESTIMONIAL FOR DOPING, I mean exactly this : maybe that doping is widespread among the athletes, but of sure is more widespread among people thinking NOT POSSIBLE running at the top in clean way, who are the one WIDESPREADING the idea of doping = result.