Schools should be compulsory because : 1. Children gain immense knowledge which founds the base of their career. 2. They meet new people and get to know different cultures, traditions, beliefs and make new friends . They get to interact with the proper school management and start to learn about the outside world which shapes them up
As far as knowledge is concerned one can get practical knowledge outside of school and can be home taught. Meeting people one can do it outside of school. Can have wide experience of the world as well as knowledge being home taught. So enrollment in school is not at all necessary.