You assume that hiring a black person to an all white team, gives much thought diversity. My argument is that it does not, if that person had a middle class background and similar upbringing.
If you hire a former gang-banger who is a wiz with eletronics, then you will have some real diversity.
You don't think that hiring a black guy will provide some useful perspective? (Or an immigrant?) I don't get why you contend that class is the only fundamental distinction here.
Tech is often focused on the minutiae of our machines, but even then information and learning is not evenly distributed. I've worked with various minority engineers and also Indian/Chinese/Persian/etc and they've all had really different views on how to approach things, how to manage conflicts, and different mathematical backgrounds too.
"does not give much diversity" isn't the same as "will not provide some useful perspective."
This is the issue I have when discussing these matters with certain people. When everything is presented in such stark black-and-white terms there's little room for discussion.
If you hire a former gang-banger who is a wiz with eletronics, then you will have some real diversity.