Having met at least 50+ people in HR who aren't what like you say, i'm going to call complete bullshit on this. I don't think you have anywhere near the kind of data to generalize an entire profession across all industries :)
The vast majority of people i've met who feel like you do are people who were, IMHO fired pretty fairly, but are ashamed to admit that maybe they weren't performing as well as they think, so they blame the system.