It's not, and the parent reply was uncharitable, yet I can understand why someone would feel revulsion at your post. It feels a bit like a parlor game with numbers. Not technically wrong, let's say—but so incongruent with what it's talking about as to leave one feeling chilled and dehumanized. In that way it does come across as minimizing.

but dang you can't put 'feeling chilled' and 'dehumanization' into rational numbers, and for a certain kind of person the inability to enumerate something or quantify its cost, is an automatic 'irrationality discount.' i.e. 'What can't be counted, can't count for much.'

Maybe that's part of why collating slavery vs. war goes wrong. Mixing even a little quality with all that quantity would change the mentality, it seems to me.

It's not. Plenty of people read what you wrote and understood it for how you meant it and also understood that the person who responded to you wildly distorted your point. You're not going to find a good conversation there. Its very sad that this type of distortion happens so often, but we live in a world where some people don't appreciate subtle truths.