I mean, it doesn't take a conspiracy theory to believe this. Athletes will do anything to win that isn't bright red line illegal, and sometimes they'll do that too -- and I'm sure the rules are primitive compared to what's possible now with enough money. Will sports make stem cell therapy illegal? Why should they? What about crispr? You think Brady isn't dabbling in that stuff?
This is already happening. HGH was already in use in youth sports when I was coming up, 25 years ago now. I never dabbled (though interestingly my asthma medication wasn't approved by the NCHSAA at the time) but I know of many that did that went on to swim at the NCAA level on scholarships. Now that HGH testing is pretty standard for WADA the rule breakers are moving on to stuff that's more and more difficult to detect. I guarantee stem cells are figuring in there if they're at all hard to detect.
It's also one of the reasons I actually believe Tatis and think his suspension is excessive. Yeah 30 years ago taking clostebol would have been a great way to cheat, but any test from the last say 15 years would pick up on that no problem. He might be a goof but I find it hard to believe he would be that dumb to knowingly take a steroid that easy to detect intentionally.
The cheaters will always be ahead of the game, always. It's just the nature of things until the WADA figures out how to cheat in ways they haven't even figured out yet, which is completely counter intuitive since what benefit do they have for that kind of R&D research.