You can easily find HR staff that are wonderful as individuals. Plenty of them.

But HR as an entity isn't about providing resources to humans, it's about managing humans as resources. They aren't there to help employees, though they may do that indirectly sometimes. They're there to help employers, and even the best individuals doing the job are still doing that job of helping the employer as their primary goal.

Even the best people can be worn down by doing the job and turn into the soulless drone, if they can't/don't think they can leave the job.

The only HR department I've ever trusted was at a home health agency that was owned by a single person who set the standards, and there were two HR employees that really were there to help balance the company's needs with the employees'. It was evident in everything they did, and the boss would abide by their decisions even if it cost her.

But! At any point in time, she could have completely done away with that methodology. And that's why HR as a thing can never be trusted