Doping would turn sport into a race to concoct the most powerful drug
Instead of a competition of athletic performance, sports would center on the capacity to concoct the most potent drug. Doping would allow the cultivation and perfection of drugs that enhance an athlete's abilities, and the more powerful and effective the drug, the more companies will want to compete for their versions of the best PED out there.
Without drugs, sport is a test of athleticism, strategy, technique, talent, and hard work. If you allow drugs to be used freely, it would drastically alter the nature of sport by turning it into a race to produce the most powerful drug.
If you allowed cyclists in the Tour de France to use a motorcycle if they so desired, the competition would no longer be about athletic endurance, but about a team’s ability to craft the fastest motorcycle. In exactly the same way, if you allow performance-enhancing drugs to be used freely in sport, it would no longer be an arena for testing athletic ability, but an arena for drugmakers to compete against other drug manufacturers over who produced the best drug. Not only would such a competition be at the expense of an individual's health, but such a proposition jeopardizes the authenticity and integrity that all professional sports are built upon. Our whole societal conception of sports is as a competition between opponents. One that is well-rested upon a sense of human nature. The winner of such a battle is one who puts in the most effort, sweat, and determination. Not the individual who can afford the latest, most powerful, and most expensive PED. By creating a space such as this, the pharmaceutical industry would be in competition with itself to provide the strongest medication it could. All the while athletes will suffer the consequences. Sports would no longer rotate around true human competition, instead, it would simply be a harmful manmade construct.
What's the difference in terms of crafting lighter bicycles, or any athletic equipment that makes it easier to compete in a sport. As training, coaching, nutrition, and equipment are increasingly perfected, the best times of the best athletes have been increasing at a slower rate and slower rate. Eventually, athletes will hit a wall. Now we are faced with the question as to how we can keep sports entertaining. Yes, we could start measuring the 100m race to the thousandth of a second, but how would these sports remain interesting and engaging if the winner of every race was decided by margins undetectable to the naked eye?  A possible solution is found in doping. And according to Julian Savulescu, an ethics professor at the Oxford Centre of Neuroethics, "The war on doping has failed... Lance Armstrong never failed a doping test, despite being subjected to thousands. Nearly every recent winner of the Tour de France has been implicated in doping. About 80 percent of 100-meter finalists are or will be implicated in doping. The fact is that blood doping and use of growth hormones have not been possible to detect, and because doping mimics normal physiological process it will always be possible to beat the test. Thus, we should embrace the inevitable, and control doping as best we can." It is through regulation that sports can still be a test of athletic ability. Moreover, why is it an issue for pharmaceutical companies to face competition as well? By creating competition in the pharmaceutical industry, sports are ensured to never hit a wall. People still need to train to make the most of their drugs.
[P1] Success in sport is currently determined by athletic ability and talent. [P2] If doping were permitted, success would be determined by the quality and potency of drugs. [P3] Therefore, sport would become a race to produce the best drug rather than produce the most athletic ability and talent. [P4] Therefore, doping should not be permitted in professional sport.