The entire discussion about entropy hinges on two simple assumptions 1) Entropy exists in D&D land and B) Magic is not capable of reversing its effects (it being entropy.)

Entropy exists in our universe and, as far as we know, we can't do anything about it. In a land of fantasy and magic its perfectly reasonable for universal constants to be turned on their head. Gravity? No thanks, I'd rather reverse it. Time travel? Sure, why not? Death? I'll just buy my way out of it. Entropy? I cast magic circle against chaos.

Nothing in D&D is absolute.

Also in D&Dland right and wrong exist as more than simply human constructs. A character devoted to the power of good can actually draw world-bending power from it.