<<Apologists can say microbes did it, not gas chambers, but the microbes wouldn't have been there if the Europeans hadn't thought they could barge in and steal someone else's patch of land>>
Doug, it sounds like you're saying there is no moral difference between:
a) Barging in, stealing land, and inadvertantly spreading microbes that kill many
b) Barging in, stealing land, and slaughtering millions with swords and guns.
The reason people try to "put this in perspective" is because they strongly sense a moral distinction between the two. I think that's utterly valid.