My understanding is that most proponents of bombing the camps argue for destroying the rail lines to the camps. Now that still leaves the issues of precision, and it wouldn’t take long to lay new track. Furthermore, those already in route might well have died or been killed if they couldn’t get through.
Bottom line, the hindsight should be left alone in this case.
We destroyed tens of thousands of miles of rails. Germans just fixed them. They’d tell everyone out and start walking.