No idea on the hard data. but... We classify competitions for a reason. The competition is more interesting when the competitors are categorized into similar ability.
You can't bring your formula1 to a touring car race just because you feel like it is a touring car.
Personally I think at the top level there should be an unlimited class. within the rules of the sport anyone can enter, then at various lower prestige levels participation is limited according to some parameter.
bad comparison - here is one better, not a perfect one...
You can't enter a car into a boating competition. The question here is: if you take basic precautions to make it the same class of boat - a modified car turned into a boat should be a valid entry - provided the engine speed roughly matches.
People worry about cars on water here, not knowing that doesn't exist by definition: any car in water has been modified from a car to be a boat. you may recognize that it was once a car - but that's vestigial shell stuff. the inter-workings are a propeller - not a wheel.
> No idea on the hard data
Great thanks!
One interesting example of this is the UTR system for tennis. It is agnostic in gender as wells as age, and tournaments can be held purely based on the UTR range