> look around the office, you immediately notice that black people aren't there.
You're right, there aren't. One in ten people in my city is black, but I would estimate* fewer than one in forty developers at my work are. But there were just as few in my college classes, in my tech clubs, advanced mathematics classes, and any other place that would lead a person to software development. I think we need to address the problems with diversity in those place at the same time as we deal with the workplace problems.
* All the obvious caveats apply. I'm not going to project an identity onto someone else.