Diversity brings value by bringing different perspectives to the problems we solve and the solutions we seek. We all have blind spots, and having a broader perspective can help us see more than we would otherwise, even where we’re unaware that we currently cannot see.
That is diversity in experience, culture or opinions, not skin color. You are also assuming that the different perspective is a positive contribution, even if in many cases it just brings more tension because people have very strong different opinions on bikeshedding. The biggest problem is when forced diversity comes at the expense of skills due to lack of supply, which is a very real thing.
Imagine the coal mine next to you that has the target to hire a certain percent of black people, 50% females and 5% LGBT: it would close instantly because it cannot meet the target. But just imagine the value of the different perspective a black coal miner would bring, compared to the wonderful perspective of the female miners.
Ok, so you think that black and white people are different for some social reasons. What if they are different in such way that black people are less likely to want to be programmers? What is even the issue here? Isn’t this also diversity? After all, not all white people are programmers and there is no reason to expect that the rate of software engineers among white people is “optimal” in the social sense.