great analogy.
Maybe I can provide some brain juice.

If you have a big motor in a tiny car it will accelerate like a bat out of hell from 0 to 30000 rpm. If its linear across the entire rpm it probably an inertia thing to fix with mass or gearing. The opposite is true as well but still linear.

I would say that rotor inertia, gearing, and mass can resolve 80% of smoothness.
timing efficiency at each specific rpm takes care of most of the rest.

you can have both problems and they compound.