It's simple dehumanization. It's not outlandish or anything, it's just really easy to notice. And the sophistry to try make them equivalent terms is also easy to notice.

For a business to need resources it means a category of stuff that can include people, tools, raw materials, etc... Using the name of a category to mean one thing inside it instead of explicitly naming that one thing is concealment. Just like how I might say "fertilizer" instead of "cow shit."

The better question is why we started concealing it. Why are we so sensitive about the words person, employee, or personnel?