Interesting mix of the politics of the medical/health industry and crony capitalism. There is absolutely a reason that opioids were pushed and things like weed were made illegally or discouraged, and it had nothing to do with therapeutic reasons. Anabolic steroids are
linked to an increase in deaths and hospitalizations, but it can't hold a candle to
opioid related deaths.
We are talking about two different issues here, though. Players can use one therapeutic option over another because, simply, those are the rules of the game. It's like asking why players can't have 4 strikes instead of 3. Because those are the rules. You can argue and debate the merits of 4 strikes over 3, or an automated strike zone, or the infield fly rule, but the one and only reason of why one thing is allowed over another is literally "because people decided that the one thing would be allowed and the other would not". Doesn't make it logical or provide a "good" reason why, but it is THE reason why.
Barry Bonds was an elite baseball player. I think that most people agree that he started using PEDs around/after the 1998 season. His career up to 1998 was absolutely on a HOF track (.290/.411/.556, 411 HR, 403 2B, 1917 H, 445 SB, 164 OPS+/159 wRC+, 99.9 bWAR/99.2 fWAR). There is no doubt among people who don't have an agenda that Bonds was a HOFer.
To answer your question you posed earlier, I would allow my child to take a non-addiction forming shot or pill that would allow them to continue playing in the moment if under the opinions of a medical professional that no lasting or permanent damage would occur as long as it was allowed under the rules of the activity. Obviously I wouldn't allow an addictive substance to be given to my child under any circumstances.
If what they wanted to give them was legal and not dangerous but against the rules of the event he/she is participating in, I would hope that I would have engrained the morals into my child that he/she wouldn't accept anything not allowed. If I had to make the choices, I wouldn't allow him/her to break the rules of the event. But, as alluded to earlier, that is an entire different argument than one of which substance should/shouldn't be allowed.