I don't read that in their comment? They said genocide has a specific definition, and the Atlantic slave trade does not match it. You are free to disagree on that point. I personally don't think it's a very good point to make here.

Instead you made some argument that they are trying to argue that it wasn't that bad, which is not based on a literal interpretation of their comment.

Can you believe white supremacists use the same kind of thinking? They also toss around the word genocide where it does not apply, assuming one against whites. If you were to say what the commenter said, they'd do the same: Instead of engaging the arguments based on merit, they'd accuse you of wrongthink.

Better to let people be honest and judge argument's on their merit rather than start accusing people of wrongthink so easily. Perhaps this is a pretty big problem in the politics right now.

If it becomes impossible to correct the definition of words without being branded as a wrongthinker, then what good is that going to do?

Words have meanings, terms have definitions. I'm with the pedants more and more. Otherwise people can simply say awful things and claim not to have meant it that way. That how lying becomes a bit ok.

Today I learned that calling something evil -- but not the worst -- is minimization.

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.