The ability to efficiently create energy anywhere and the maximum level of power that can be output seem critical.

Creating energy, but only in specific locations, doesn't have the broader social impact.

And similarly, many applications require a minimum level of power (say, 2x horse) before they're fundamentally transformed.

The industrial revolution was, from my perspective, an ouroboros of the means to produce power increasing our means to produce those means, and out of novel raw materials.

Or, in other words... at some point the Romans had deforested their environs. https://en.m.wikipedia.org/wiki/Deforestation_during_the_Rom...