As others have mentioned, it is a narrow definition. The idea is that the only fluctuations occur due to uncontrollable factors (weather) which, in all fairness

As others have mentioned, it is a narrow definition. The idea is that the only fluctuations occur due to uncontrollable factors (weather) which, in all fairness, do impact carbon-based power too (to varying degrees). So a war in the middle east or a trade embargo won't impact the price per kwhr. Whereas a tornado would impact both wind and oil (even if just by slowing down the deliveries). I would argue that wind (and solar (not so much hydro)) are much more susceptible to weather impact, but with sufficiently large capacitors/batteries that can be minimized.