Feeding kids is hard. Providing a framework to know what exactly is a parent's job when it comes to feeding helps provide guidance to more relaxed and less anxiety filled meals. Placing your reassurance that as a parent you have done your job as opposed to seeking that reassurance by having your child clean their plate, helps provide a path for your child to develop a healthy relationship with food.
Parent's jobs includes what foods will be served, where to eat, and when to eat for meals and snacks. Kid's jobs includes what to eat from what is served and how much to eat.