I agree that it's a somewhat unfair generalization that paints a harsh picture. The core point of the argument still holds though, I think. A cynical response might be to say that the difference is the employer is accounting for longer-term replacement hiring/training costs, rather than short term value extraction. The optimization has new parameters but the structure of the relationship is still fundamentally transactional. I don't really think that's how things generally run, though.

Both parties should want a place that's enjoyable to work over the long term, yet sometimes the company will have to make hard decisions. Priorities slip or people are straight-up unable to avoid, say, laying off half the staff. Framing and context matter, as always. "Your employer is not on your side" is hopefully not a statement about the day-to-day interactions with your boss, or even a statement about company values, but it can serve as a reminder that there's always a line somewhere, and, intent aside, your best interests may simply fall on the wrong side.