Thats because the only guys who can really do it are the junior/senior guys.
Boys just dont develop the same, a 13 year old girl may be in the body theyre gonna have forever, but a 13 year old boy may just be starting puberty.
Late high school guys can generally do the basics of partner stunting (for example I can "toss extension" but it's really more of a toss half of the way between hands and extension and then I press up.) and mid to late college is when developmentally theyre at the point where theyve gained the muscle mass to do the complex stuff.
The guys in late hs who can rewind to cupie that everyone always drools over tend to not be able to tumble for a similar reason, just reversed.
For me, I went to college tryouts ashamed because I thought my stunting was so poor. When the coed stunting section came up I was embarrassed to go.
If you want me to back/base a sick 1.5 up to stretch double, Im your man. But I cant partner stunt my way out of a paper bag.
But, when I went I saw that all of the other hs seniors who were going could pretty much do the same thing I do. And thats all the coach expected. She told me that most guys come in not being strong enough to do hardcore partner stunts and it takes a year or two for their bodies to finish developing.
I got a personal trainer and worked my butt off and scared the crap out of my dad (a pediatrician) and realistically, if I ever do bulk up any more, it will be later in life.
Sorry, rant over.