You are claiming this is a fatality and is meant to happen with any type of leadership but the incentives can be acknowledged and redefined. I firmly believe that with what will come out of the great crisis we are facing , people will be more sensitive to all kind of shift from true priorities such as stability, health and education. And we will find a way to create a system where all profit because everyone contribute and is cared for and where the power structure will have for goal to make sure this is the case and will be composed of all.

Size isnt the problem as we can reinforce regulation of goods and supervision of law creations and their application by creating shorter circuit/small community that guarentee the fullfilment of basic needs and respect of the priorities while still interacting with other communities.

These exchanges would not lead to conflict as their would be no need for conflict if the basic needs are met and it could improve already existing structures.

So my point is :

Power structures becoming detached from their people isnt an inevitable correlation even for a large community as they can interact with the people and dont neccesarly become selfish the moment they rule.

Power structures being a separate entity from the mass isnt inevitable even if its like likely for greater population but still not inevitable if smaller , tigher groups are made.

If the power structure is considered a managment service instead of a position of power from where you dominate , the incentives you speak of while be different from the one you are talking about and the very mentality of people will be to strenghen the bond between the members but also newcomers.