I personally think that teaching schools dialects could be hard on an individual because it is a professional language and it is like a college level. I personally think that teaching dialects could be hard on a student because they are young and that would be a lot on that individual.
Schools should not teach different dialects of a language because it is unnecessary. Students only need to master the standard variety of a language. The purpose of public education is to prepare children for a career. Learning unnecessary dialects is not necessary for this. It would take time away from more useful subjects.