I don't disagree with this at all. But I don't read the comment I was responding to as having come from the thought process of
"If Visa/MC charged a 1.5% cut instead of 2.5%, the economy would be 1.5% more productive than it is now, which means that, compared to that more enlightened hypothetical world, the non-Visa/MC portion of the economy is only 97.5% what it should be."
If you think credit is related to the size of the economy (and I do), you need to ask, where did that 2.5% number come from? Saying that Visa's entire fee represents nothing but a drag on the economy is very much of a piece with the historical loathing of merchants and usurers, who, as anyone could see, did not create value.