I'm not opposed to offending others. : ) Just be aware when you do, and why you're doing it. The parent post simply seemed blithely unaware of how deeply hurtful the phrase can be to people. (Imagine typing that phrase out every day when literally your own great great great grandparents were dragged here in chains and were considered the personal property of someone. That's simply f'ed up and would suck beyond belief, and not even being willing to acknowledge that harm is crazy to me.)
So, I have clinical depression, which I take medication for. I've worked in neurology, my formal education is in psychology and neuropsych, and growing up I've known more than my fair share of people with some form or other of mental illness. In short, I live it, I've studied it, I know it.
Your comment reminds me of someone on a chat channel who had a nagbot that banned the word 'crazy' (amongst others). Why was 'crazy' banned? Because it might offend crazy people. Being one of those, and knowing people like that, absolutely no-one who would be labelled with the moniker 'crazy' would be offended by the word unless it was directed at them. The idea that a schizophrenic friend would be 'deeply hurt' if I said 'the traffic this afternoon was crazy' is utter nonsense. This forbidden word was forbidden by someone who clearly doesn't associate with the kind of people that were being defended.
And so it is when your black American engineer types the word 'slave', suggesting that their self-identity is so wrapped-up with the identity of a person that their grandparents grandparents barely knew, that they would find a non-directed under-the-bonnet technical term deeply hurtful. It's disturbing that you consider these people you're supposedly defending as being so incredibly emotionally fragile.
Yeah, I actually dislike it every time myself, though that's not hugely important to me, nor why I commented.
There was some interesting commentary in this thread about cultural appropriation and whatnot, which seems to me to be beside the point. My intent was only this: if there are other people rightly upset by something, it doesn't matter if you're not, it doesn't even matter if the majority are not, it's still valuable to have empathy for those those that are. That's all.
