What a non-story, preheating the oven is not because of the heating element being slow to heat up... Even the slowest heating element is at temperature within a minute.
Preheating the oven is so the walls and air are all up to temperature and that time will be largely unchanged. The halogen heating element of my 20 year old lg solardom oven reaches 2500°C in about two seconds, but preheat takes about as long as any other oven (with the same power)


Btw For most dishes preheating is unnecessary, you just have to extend the time a little.

Given most oven baking is done at around 160-220C, I assume this is for those that like super-char.