In the US, it's the government that created the free market, and did it for the people. The US government is "of the people, by the people, for the people."
...Or at least it used to be. Now maybe in 2020 now, "people" can be replaced with "corporations".
It is upsetting to some because some people assume a resource can't have feelings. Like saying "women are objects." Obviously this isn't what is meant with Human Resources but in today's world people want to argue over naming conventions as if their perspective of a name or even a definition is the only right one because it fits their goal. Make no mistake if you called Human Resources instead Team Builders someone would eventually a few years down the road get mad because you can only build buildings with objects and so the name doesn't do justice to the feelings of people again.
It's simpler than that. Things and people inherit the properties of what they're called. That's why slurs are so powerful. e.g. n-word, c-word.
I don't believe I've ever seen a post on HN about how wonderful a Human Resources department has ever been, or ever treated anyone fairly. Feel free to prove me wrong here.
If you can dehumanize humans, then you can treat them like objects. It's easier to do firings or layoffs, or cut back on pay raises and benefits.
The problem is not that human are resources. They are.
But from a production point of view, the problem is when you think that a human is equivalent to another with the same title and they are easily interchangeable.