You do understand that the state is entrusted to fix problems in society and that having some pockets of society not contribute as well as other pockets is a problem, right? Pretending a problem doesn't exist ("ignoring their backgrounds") is not a good way to solve a problem. That is the error in that statement, not the "treat everyone the same" part, which is merely overly vague. If you treat everyone with the goal of trying to get them to succeed, this necessarily involves understanding the backgrounds of the people you're trying to help. Ramanujan didn't have a background in formal mathematical proof, but Hardy was able to get him to do great things by understanding his strengths and filling in the gaps.

Typically, the people against programs that attempt to solve these problems assume that some pockets of society are unfixable. Korea had a literacy rate of 22% in 1945. These people, had they existed in 1945, would have said, "Well, that's just the normal order of things. No need to try to fix it because you can't."