that makes it sound like a natural law, an inevitable process. is it, though?

At least within social structures, I would argue it is, much like power vacuums and game theory.

Even monkey troupes and wolf packs have central power figures.

first we should clarify what we mean by 'power'

in this context, 'energy over time' is not what we are talking about.

I'll leap to say ultimately, it's probably quite like mass and gravity; the end observed effect of mass lumping together is like this 'observed' effect of power agglutinating. but which is the mass? and which is the gravity?

Yep, so it doesn't "just happen" - you need to build a pump first, and you need to keep it running for the water to flow uphill.

But it can be done.

The switch for the water pump, electricity connection, etc., must necessarily be centralized.

It's impractical to design a pump operated by millions of switches or fed by millions of electrical cables.

It's less efficient, sure. But it's eminently practical if your goal is to avoid hydraulic despotism long term.

It would be so less efficient that you could simply buy a 1000x more water pumps for the same price. No one sane would choose a water pump with a million switches over 1000 of the same pumps with 1 switch each.