Because the US public school system was based on the Prussian model. In essence, Rockefeller wanted good little obedient soldiers and factory workers that would give deference to authority. That's part of the reason why western education has so much overwhelming classwork, homework, and rote memorization in it because it's less about giving people information they're expected to maintain and more about breaking people down, exhausting them, and getting them mentally to a point to want to take shortcuts in thinking.