This simply is the opposite. Think if everyone took PEDs...
- Genetically some bodies are more apt to have a higher muscle density.
- Some bodies can carry more muscle.
- Some bodies have stronger ligaments and cartilage.
So everyone takes PEDs, everyone works out the same, and let's take skill out of the equation (for the sports that require skill). Then you will simply have the tallest, most genetically available people that are the best athletes.
Out of this "supreme" group, they will lift, run, whatever. Their body will hit a building limit based on activity. This limit has probably been hit by some current athletes who have taken PEDs. Then out of this "supreme" group their knees will start to blow out, their hip abductors will not be able to handle the torque, their elbows will blow...
And then you are left with the people whose bodies whether genetically or luck don't crumble with the extra muscle, speed, and tension. This is pure genetics and the exact opposite of a level playing field. If everyone does PEDs someone under 5'8" just never runs track or plays most sports.
There is no research for things like this. Your research is the baseball players that have had hip issues after PEDs, the football players that tear their knees up, and some golfers (who have mysterious hip injuries and go from best player in the world to dud). Your research is in the news everyday.