Something doesn’t sit right with the idea that the Force is limited by the physical vessel through which it is channeled, at least where the light side is concerned. It is my understanding from the OT that the limiting factor in any feat of the non-Dark Side Force is the belief of the acolyte, with training as a way to allow for greater belief. Luminous beings are we, after all, not this crude matter.
The Dark Side, on the other hand, may very well have some physical cost, as both of the Dark Side users in the OT were either horribly mutilated or clearly insane.
This is one reason why Luke’s death is so inexplicable to me.
Yes luminous beings, aka the soul or the spirit. The crude matter is what died. I admit that it feels more “correct” that the bad guys feel ill effects more than the good guys, but there are no real rules beyond what is shown. In theory the “quicker, faster” dark path is damaging in comparison to the more disciplined method. But there’s nothing to say that using the greatest powers when the body is already old shouldn’t have side effects. It’s all vague enough to work for me (well OT and ST anyway).