Collegiate athletics is organized under a league called the NCAA. The NCAA sets rules requiring players to have certain ACT/SAT scores, GPAs, prohibit players

Collegiate athletics is organized under a league called the NCAA. The NCAA sets rules requiring players to have certain ACT/SAT scores, GPAs, prohibit players accepting compensation for participation, etc., and there is a complicated enforcement division that metes out discipline for violations. Schools can technically do whatever they want, but in practice this would put them in violation of agreements with the NCAA, they'd get kicked out, and then they'd have nobody to play against.