Warm ≠ Preheating. Warm is an extremely low setting that is intended to warm what is in the oven without significantly cooking it. Preheating is the cooking step of letting the oven get up to the target temperature before you put the food in. Most recipes are designed to be cooked at the listed temperature, not cooked at a temperature that varies from room temp to the listed temperature at whatever rate your oven heats at.

P.s. You don't have to be an asshole.