It's just another piece of political theater that's been going on so long, everyone's forgotten why we started it.
It used to be that Soviet and East German athletes won all the power events because they were pumped up on officially-administered steroids. This was something to do with Soviet manhood and during the Cold War, it was obviously an unacceptable situation. However, when Americans tried the same thing they found their manhood disappeared, which made them formidable competitors in womens' events but did not solve the manhood problem. So the Americans started a campaign against drugs in sports which when strictly enforced, allowed Americans to pick up a few medals when the actual winners were disqualified. The resulting sounds of the American national anthem coming from European sports stadiums damaged Soviet manhood to such a degree that the Berlin Wall collapsed and the Cold War ended. However, this took so long that nobody in charge of the drugs policy could remember why it started or what it was for, although they very much appreciated the fat brown envelopes being handed to them by the testing labs. So on the grounds that if a little bit is good then a lot must be better, they extended the drugs ban to just about any chemical not found in a diet of green vegetables.
In the case of Mr Armstrong, I'm quite sure the steroid's muscle building properties were quite secondary to him, and what really mattered was that they made his manhood shrink to the size of three raisins and disappear into his body cavity. Have you ever seen one of those bicycle seats?