That's the thing. When we are talking about current, we are not talking about how many electrons are moving, but about the transfer of energy from one place to another. The water analogy just doesn't work, because while the current itself flows at nearly the speed of light, the electrons themselves move very slowly. In an AC current, the electrons don't flow at all. They vibrate. And in a liquid, the energy transfer can just as well be by means of anion flowing backwards, as cations flowing forward. Yet we think of the current as only flowing in one direction. You see the problem? Trying to think of electrical energy as a "flow of electrons" OR a "flow of protons" completely skews one's understanding of what is taking place.