I do not doubt that some out of control guards did some things, but millions of jews were not killed in this manner. That is pure fantasy to nudge the Nuremberg trials towards crushing Germany through takeover, sanctions, repayment and reparations.
http://en.wikipedia.org/wiki/The_Holocaust
"Some 60,000 prisoners were discovered at Bergen-Belsen by the British 11th Armoured Division,[265] 13,000 corpses lay unburied, and another 10,000 died from typhus or malnutrition over the following weeks."
So they find 60,000 living and even after administering medical care 10,000 died of typhus and malnutrition. That's 10,000 deaths that had the war not ended when it did, would have been blamed on the gas chambers. That should stop and make you think about how many "gas chamber deaths" were actually natural causes as a result of the living environment.
If you want to make the argument that Germany should have just opened the gates and let them out when the supply lines were cut off, that is definitely an argument to be made.