Well your so called obvious is just your confirmation bias ... It means nothing unless you have evidence. Do you have any?
I gave it to you. When you select new hires to speak French, your workforce will, well, speak French. When you select them based on machining ability or mechanical aptitude, they'll have these skills as well.
But when you select based on race and gender -- well, you get a diverse workforce. And Boeing, since implementing their strict DEI policies, has gotten just that. Race and gender in new hires, race and gender in promotions to management, and race and gender considered in every retention and firing decision. They've gloatingly reported this on every annual DEI report the company has filed for the last decade.
The results on Boeing's products -- as well as the conclusions of government oversight reports -- bear out the obvious conclusions of such a policy. This new "diverse" workforce is poorly trained and qualified.
Now, let's consider your competing theory that "cost cutting". The problem with that belief is that there hasn't been any such cost cutting. Labor costs have risen steadily, workforce retention of existing workers -- especially among minorities and women -- is up sharply, and profits are an endless stream of negative values.