This complaint seems like its shooting itself in the foot - discrimination isn't inherently bad. When you hire, you discriminate based on ability. When you date, you discriminate in a number of ways like beauty, personality, etc. If you're selling ads for wheelchairs you want to discriminate for people with disabilities. If your houses aren't wheelchair accessible, you want your ads to discriminate against people with disabilities. If there are "majority-minority zip codes" then maybe advertising against the demographic is a waste of your time and money.
The idea that we should operate without discrimination is a toothless platitude with little bearing on reality. It is not Facebooks responsibility to change reality because they are able to accurately quantify and qualify it's existence, and sell ads based on their findings.