Major League Baseball owes the minor leagues as we know it to the genius of Branch Rickey and his network of Cardinal minor league teams in the 1920s and 1930s. He did this to compete with the East Coast, especially with New York I presume, and his influence continues to this day.
MLB owners saw the value in a minor league system, because these professional players would not be subjected to the NCAA's nonsense. This was understood decades ago by owners as a group. The NCAA has a far outdated set of standards and rules for basketball and football players. Because baseball takes a few years to learn at the major league level, the minors had a place. There was never a need to create an impression of scholar/athlete for the sake of baseball players. While it is still true that ballplayers need to move on and get real jobs more often than not, this fact was recognized and overcome by major league players since the start of professional baseball itself.
Meanwhile, basketball and football players rarely need a five or ten year learning curve to learn which niche to fill on a big league roster. By age 23 or so, college basketball and football players have reality thrust upon them by coaches, family, and even girlfriends, all of whom suggest finishing college.
It takes a while for a young player to give up the dream of major league baseball. A player may gradually become a contact hitter, learn to pitch, catch or learn to play the outfield, and especially when big bucks are still possible at ages 25-29 or so. The minors provide the venue for it.
Show me a 25 year old college basketball or football player and I'll show you a master at deception over his coaches and the media.
Catfish Hunter, RIP. Mark Fidrych, RIP. Skip Caray, RIP.
A fanatic is someone who can't change his mind and won't change the subject. -- Winston Churchill.
Experience is the hardest teacher. She gives the test first and the lesson later. -- Dan Quisenberry.