I'm not sure how your extreme example is helpful. No one has made a suggestion like that.
For example, road bikes have different frame shapes that are suitable depending on your torso length compared to leg length.
Of course, the natural next step would be allow some flexibility (different frame size but same material), but you can see how that could be a slippery slope of legislation and lobbying that would end up in a similar situation to where we are today?
You -should- be able to just mandate Hubs and cranks to get around this.
Or make sponsors provide a 'slew' of wheels and cranksets for all their riders (i.e. spares as well) that can get inspected before the race, and are randomly distributed between the riders sponsored.
Buuuuut UCI hasn't even figured out doping, so lol
Well yes, but different sports are also better suited for different individuals. It's just making the equipment part of the definition of the sport.