Dude, instead of using master's degrees as a proxy for some standard that was fair or unfair and how changing it either led to the betterment or detriment of the said groups, why don't we just get specific on the topic at hand? What, exactly, are the systemic barriers that are in place that prevent X-type of person from joining the AF and achieving a successful career? Personally, I don't think there are any. I think arguing by analogy in cases like these leads us literally nowhere. Get specific.
On the topic of master's degrees, however, using them in order to determine whether or not someone should be chosen for advancement really only came to pass because it was a way for the promotion board to hit the easy button when they're examining a stack of (basically) equivalent OPRs. Let's be completely honest: we have developed and placed a lot of faith in metrics that we convince ourselves (i.e. promotion boards convince themselves) accurately measure whether or not someone should be promoted. In actuality, however, these ridiculous processes exist merely as ritual to legitimize a purely subjective process. This bullet means X, this bullet means Y. It would be better (more objective) - it really would be - if your OPR was merely a rank ordered 1, 2, 3, ..., n, out of N, and what got sent up to the promotion board was a list of the rankings you achieved over your career along with a recommendation of whether or not you should promote. The promotion board would literally be purely objective, and we'd be able to side-step the little temporary, subjective universe that gets created during the promotion board card game.
And finally, I will proceed to flog myself for the overuse of the word 'master' in this post - it has recently been decreed that this word is decidedly 'unwoke' and its use is somehow discriminatory, triggering, inflammatory, and/or otherwise offensive to certain groups of people. My bad, tonight I'll go to sleep in my primary bedroom.