Answer:
To enable the government to design their curriculum based on the demographic.
Step-by-step explanation:
If we allow national powers to control established public schools, every regulations made by the federal government should be followed by All schools in United States.
In hindsight, there might be nothing necessarily wrong with it.
But, United States consisted of several citizens' demographic with different cultures, economic background, and local conditions.
This is it is better for state power to control the public schools instead. it allowed each schools on specific district to design their curriculum based on the demographics of the students and local problems that they might face as soon as they graduate.