The NFL and NBA have multi-million dollar minor league systems they use for free - college. Neither will ever undercut these talent providers.
For comparison, MLB teams spend an estimated $22 million per team for the AAA, AA and high-A teams. That is $66 million for the upper level teams. The MLB teams pay ALL the salary. An estimated 12 teams, all AA or higher, are profitable, but the profits go to the actual team owners, not the MLB affiliate.
Further, the low-A teams and below (rookie ball, short season, Dominican teams, etc.) cost another $5 million per, with no profit to worry about. Teams thereby spend on average $80 million per season on minor league franchises.
Football and basketball teams get that for free, and with competition that is much better at predicting future success than the current high school/college programs do for baseball players. NFL and NBA are smart enough not to #$%@ with the college goose laying the golden eggs of future players, at no cost to the professional franchises.