AC was used to increase distant transmission and use thinner lines, unless something changes in the GW ranges of power transmission.
I may be too short on why DC works here but the reason it had to go to AC back then was we didn't have the designs and technology to push DC long distances.
In short, AC worked in the 1880's and forward because the basic element to step up and down the voltage was the AC transformer. No transistors required and this meant you could push the voltage up and the current down for long distance transmission on smaller gauge wires.
You have that nailed.
But today we have a lot more technology to deal with DC to DC conversion that didn't exist in the first hundred years of electrical production.
The same laws apply to DC as AC about voltage and current. What's changed is that we now have the circuitry and power management controls that are recent inventions.
It was only a few decades ago that a patent by AT&T expired about PWM ( https://en.wikipedia.org/wiki/Pulse-width_modulation ) and that opened the door to power supplies that were not "linear" designs. This was a very big deal.