We avoided attacking the infrastructure of the holocaust because it was believed that we would be diverting resources to attack what would be repaired by Germany anyway, and that it was best to keep those resources dedicated to the war to end it quicker and liberate the camps quicker. There was one incident where Allied bombers bombed a concentration camp, and that was only by accident.
What if the Allies targeted the concentration camps, bombed rails, etc as part of the war effort, and made them a military objective?