In most companies, said hiring manager would be the one pounding sand.

HR works for the company (aka the owners/senior execs), not a random line manager.

If they like what the line manager is doing, then that’s cool.

If they don’t, unless execs or ownership cares, they’ll happily set said line manager on fire for their amusement just as easily as a random employee.

And since line managers need HR’s co-operation to hire/fire in most places, they’ve got to manage that relationship very carefully or be really screwed.