That's an awfully friendly reading of what's going on here. I'm not a biologist, much less an evolutionary one, but what I've heard is that explanations for the benefit of the whole group tend to be wrong or at least met with extreme skepticism.

Here's another reading: It could also be that we're wired to exploit situations of power. Isn't it convenient that empathy is reduced when you're more powerful, making it more likely for you to (ab)use that power in your own interest? That seems awfully likely to improve your personal reproductive success...