There were plenty of agricultural societies that were also fairly egalitarian. One interesting bias we tend have is that we identify "advanced" societies by how much they look like our own. This leads to a general bias towards deeply hierarchial, stratified societies being described/perceived favorably in media against their less familiar neighbors.

Hierarchies in society get stronger, deeper, and more complex the larger the societies are. There is a function to hierarchy, it doesn't exist for its own sake. In small groups those hierarchies are not as useful so they aren't as pronounced.

Think of the neural complexity required for an amoeba to navigate with flagella vs a fly to navigate with wings. Even the fly's complexity is dwarfed by, say, the neural complexity of an elephant's control of his trunk. And that pales in comparison to the neural complexity required to get a spacecraft into orbit.

Complex behavior requires complex systems and complex systems require the simplicity that hierarchies provide.

I think the argument that “1% of the pre-agricultural humans didn’t hoard 90% of the bronze” is more of an issue of logistics than desire. Even apes and chimps have hierarchies.

In comparison, yes.