If there's one bit of information I want you to take with you, it's this:

The personnel department isn't just filled with "people" people --it's filled with "'people' people" people.

It's a department, and it has its own budget, so that means it's out for its own survival. It competes with your department for company resources, and it's in a position to stack the deck.

It makes policies designed to favor "people" people.