What about absolute monarchies or ultra-totalitarian systems revolving around one man, like Stalinist Russia?

Human mind loves repetition. The power to rule over a society comes from its traditions. Gold and steel can allow one to change the traditions. Faith can work too, but good luck pulling it of. Faith is closer to a force of nature than a tool.

You can't have a big hierarchy with only one man giving all orders, it's physically impossible. And since one man can never be the only one giving the orders, one man can never personally hold all gold and steal in a society.

Whenever a ruler does something new, people will look at him. They look, and think, and act in accordance with their natural interests. The more people look at you, the more they think about your resources, the sooner they will find a way to redistribute them.

Become invisible so the people can't look. Become irreplaceable so your resources can't be redistributed. But you can't, nothing can be perfect.

So you believe that every system inevitably develops an elite class that rules from behind the scenes instead of the legitimate leaders?

The elites don't rule, they just gather resources they see, and use them for their natural interests. All people do this. Let them look at your resources long enough, and their mind will develop a way to gather. It's natural.

Classes seem powerful because they are harder to kill than a mortal, their functionality is harder to replace. Thus, even though people can see a class, and their mind will search for ways to gather the resources, it can just fail.

The good thing is, a class doesn't have a brain, thus it can't oppress you efficiently. The bad thing is that a class doesn't have a brain, and thus feels no guilt and can't receive pleasure from altruistic actions. No pleasure - no interest.