> Space (with a sunshade) is a nearly perfect medium into which to radiate heat, in the sense that there’s nothing better.

There is radiation but zero convection. As anyone with an oven or PC will tell you, even a very tiny fan makes a big difference in the ability to dump heat. We're not putting our PCs into vacuum chambers for a good reason. A small fan in your oven not only makes for more consistent heating in your food, but it requires less power