Part of the learning environment in school is how to navigate the social world. In the adult world, most of us have to associate with the general public, with peers, co-workers, our bosses. 
Sending kids off to the library to learn might work for select few. Some kids need the structure of school to have any chance at all of getting an education. Involved parents who model exemplary social skills go a long way in achieving education and later success, but it is, unfortunately, not a requirement.