I don’t know about the Majors but they NEED their Captains...
So let me get this straight, when Captains do well and get actually get promoted, its okay to kick ‘em out?
When I worked in a university setting ... in Cambridge, MA ... I observed that many extremely bright young people arrived on campus as Freshmen. They were noticeably less bright by the time of graduation. Of course, some stayed on and pursued their Master's degree -- they were easy to spot because they knew almost nothing and were confused by simple questions. And obviously you had students in Doctoral programs -- they couldn't work the copy machine.
Based on my knowledge of the Armed Forces, I would say it works the same way.