They may not have been thought of that way, but I've very much seen them treated that way.
Pressed on all sides, dealing with unreasonable demands from above, and with internal competitors and naysayers to fight off, even the most enlightened manager may sometimes behave in ways that treat people as easily replaceable.
Even if intellectually they know they aren't.
I have a theory that a lot of the terrible mismanagement we see with modern American corporations comes directly from HR. Didn't W. Edwards Deming say that companies would be better off just eliminating their HR departments altogether?
This is in stark contrast to when I was consulting in LA/OC, where I was constantly having to justify my not so high hourly rates/fixed bid projects.