If you own a business it doesn’t pay (in the long run) to hire women or blacks. It’ll cost you more than their worth to defend yourself after they play the race and sex card (if/when) they’re fired for incompetence.
I would disagree with your statement by rephrasing it: “If you own a business it doesn’t pay (in the long run) to hire incompetent women or blacks...”
You can certainly fire incompetent white males, and God knows, there are plenty of them who are incompetent as well, but I suppose I would have to agree with your post in that they are easier to get rid of.