Students who owes a dormitory can learn on their own about how to take care of theirselves and also be more responsible. As they learn and get responsible, they get mature like adults and could survive on their own, without parents. In conclusion, students learn more when they live in dormitory on their own.
When a student gets into a dormitory, of course no parents helps are coming, it is absolutely helpful for students to be independent which they can handle all their stuffs himself. In dorm where a lot of friends live there, they can still have chat and doing something interesting with them. Also they can loyally help him to handle some concerns. They must need this.
I think dormitory is not helpful to schools because students will need their parents to care for them. If there're in high school than maybe yes but elementary school kids? Absolutely not! Students might get homesick or hate their teachers because it's like you're MAKING them live there which you are.