The bar of intensity and speed has continued to grow in AS and there's no denying the size of flyers has gotten smaller in the process. While HS cheer has done fine with the narrow height/weight gap, its intensity and speed isn't the same as AS. We came from a gym that preferred putting age groups together by HS, MS, and elementary, and it was competitive for a long time. However, as the skill bar continued to rise, we saw first hand how much difference those smaller flyers on other gym teams made when it came to stamina, speed and skill ability.
I see pros and cons. I can't/won't speak for other gyms, but as our gym adapted to allowing the younger minimum on Sr teams, the athletes just naturally sought out their age/maturity groups for friends during breaks and comps. While practicing, talking was at a minimum. The bigger challenge, IMO, is SM, private messaging, and porn exposure on phones that defy age, walls, and states. These governing bodies will follow legal advice and then try to appease parents and gym owners, but I hope coaches expectations of athletes physical ability and routine intensity will be reflected with the changes.