You've touched on the strawman about HE, but you've misidentified the source. It is the Marxists that want you to believe the psychopath claim, in their desire to stereotype capitalism as blind greed. Good capitalists that understand economics will perfectly happily include happiness and such in the value functions they use, because it turns out economic theory stops functioning without that assumption; it's built in at the ground floor. By this, I mean, the math stops working, at the deepest and most profound level economics is built on the idea that entities have different value judgments, down at the microeconomics level where economics is actually meaningful.

And note the Marxists then wish to slide in the idea that they ought to get to set your value function, when you aren't looking. (Which is part of the silliness at the core of the whole idea when they think they can set the same valuations for everyone, because, again, the math stops making sense and, what a surprise, indeed systems that truly attempt to function in a fully Marxist manner really do break down in a horrifyingly complete manner, as if they were trying to build an economy on the proposition that 1+1=3.)

The strawman idea comes from the Marxists, who generally don't want you engaging with capitalist theory particularly fairly, since they would lose a big rhetorical weapon if you do.

You can not understand the anger about HE until you understand that Marxists desperately need humans to not behave "slightly irrationally under some circumstances" (the real scenario) but need humans to be profoundly irrational, so they can justify their handing over all sorts of power to the government so they can save everyone from themselves. Of course explaining exactly how the government will transcend being made out of irrational humans is conveniently left unexplained, since that is impossible. But, if humans were really profoundly irrational, we wouldn't be having this argument, because our species would be long dead. People who want to believe that people are profoundly irrational on a massive scale must grapple with the problem that such behaviors lead to death in the real universe, and tend to be evolved out pretty quickly. (This is where the "amusing" comes from in my other post; humans are not entirely rational, but we've been tuned to be surprisingly rational in many ways... our claimed reasons however have not been so tuned.)

So the problem with HE isn't that he's utterly, utterly nonexistent... the problem with HE is that it's a slightly imperfect model, and iterative systems like the economy being what they are, that imperfection can end up magnified in surprising nonlinear ways and have bizarre consequences, in a system that often has nonlinear and bizarre behaviors even if everyone was totally rational. So it important that science is done to determine the ways in which real humans deviate from HE... but these will generally be in relatively small ways, rather than the massive total failures of the model that the Marxists are searching for.