I could have been clearer in the grandparent. As stated, the great-grandparent can be taken several different ways, and most of them I have trouble with.

One interpretation is that you're essentially judging a business by its expenses and nothing else. I agree with you that proportional measures are sometimes dodgy- oftentimes it's better to look at profit than profit margin- but just because there are more slaves today than there were when the world was much smaller doesn't mean that things are worse now than they ever were in history.

That suggests a deeper contention: I think pure harm-minimization ethics are, well, bland.