Behaviourally modern humanity did evolve to live under the conditions of the egalitarian, nomadic Stone Age. But our brain structures carry the older, mammalian functions that evolved for millions of years before that. So it's a question falling back on Stone Age norms or on more primitive mammalian ones.
Of course, the societies we build for ourselves have the potential to transcend both of those worlds, which is why we often feel alienated in our big cities. We long to be nomads at one with nature and we simultaneously long to serve under a master in a dominance hierarchy (or to be that master, assuming we're sociopathic and sadistic).
These longings are as self-contradictory as the layers of the brain. Our inner nature is divided against itself, as has been recognized by dualistic religions and philosophies long before cognitive science showed our rationality is like an island surrounded by a sea of irrational biases, intuitions, and leaps of faith (by heuristics rather than just algorithms or logical deductions).
Somehow, our sedentary civilizations have reverted to the much older and long-lived mammalian norm of the dominance hierarchy. That social structure of the pecking order is the natural, default way of distributing power in a group of social animals. Even humans who know better fall back into those routines, because progress is new and scary.