There is doping and there is doping. I don't see why athletes over say 30 can't do some mild oral steroids to bring them back to the testosterone levels of a 25 year old. Would help with recovery and probably lessen the severity of injury.
Men have lower testosterone levels than their grandfathers, there are many possible causes but the treatment I'm talking about only really brings you to a bit above where grandpa would've been.
Because you've never met an athlete, I guess. None of them would stop at "mild".
The goal isn't to get them to a superhuman level, just to level the best genetics produce.