Actually Kansas does allow schools to remain together — in team sports.
I know at one time, for example, Lansing did not have girls' soccer and their athletes shared with Immaculata. All-Stater Cara Medill was a Lansing student wearing green and white. Team sports stay together and "individual" sports such as swimming and track do as well so you aren't breaking up relays.
Only in the case of wrestling, cross-country or something else are they forced to spilt up. There are no conspiracy theories out there; it's just a reality.