It's circular because it's a circular pattern that reinforces itself. If schools had a large amount of resources or didn't need to scale efficiently they wouldn

It's circular because it's a circular pattern that reinforces itself. If schools had a large amount of resources or didn't need to scale efficiently they wouldn't need the structure and if they didn't need the structure children (and staff) wouldn't become dependent on it. That said there certainly are people that need structure to learn (particularly what they don't want to learn). There are several disorders or disabilities that would make unstructured learning incredibly difficult or impossible.