Heating water-rich food uniformly and gently from the inside rather than by propagating heat through the food surface, which is a rather unique property that allows specific techniques and results.

I just do that on the stove or in the oven. I haven't owned a microwave in years. However, I'm not opposed to them. They are super convenient. Way less concern for burning leftover soup in the microwave that takes half as long to reheat my soup. Lol.

Actually I partially cooked a pumpkin pie in one. (Only the first stage to soften the squash.) It was faster and used less electricity.