@flyermom i think you are sorely mistaken on all of these top level 5 teams. I would find it hard to believe that these large gyms are just cutting tons of level 5 athletes so they can "stack" a team. Also, these large gyms have multiple level 5 teams that they are trying to make competitive.
For example, the following programs have multiple worlds teams that can be very competitive in their respective division. These do not count their intl open teams which can also pull athletes from the traditional sr divisions (i think everyone one of my examples has at least one version of an intl team going to worlds)
Cheer Athletics Sm. sr. and Semi Coed
California Sm Sr Sm, sr limited coed,and Unlimited Coed
Stingrays Sm Sr, Lg sr and Large Limited Coed
World Cup Lrg. sr, Lg limited coed, and sm sr
CEA Lg sr. Sm sr. unlimited coed, and I think they have some other worlds team
Md Twisters Lg. sr. sm. sr., sm limited coed.
So, who exactly is "stacking" their worlds team? It seems that the large gym has to spread the wealth between their worlds teams to be competitive.