The purpose of education is development of the person because when a person is taught, they can associate their knowledge with everything else. In order to have a good job or to do the simplest thing you have to have some type of education. Like stated by Hirsch regarding education, "Why is literacy so important in the modern world? Some of the reasons, like the need to fill to forms or get a good job, are obvious that they needn"t be discussed. But the chief reason is broader. The complex undertakings of modern life depend on the cooperation of many people with different specialties in different places. Where communications fail, so do the undertakings" (1.4). Different people have knowledge about different things depending on what they study which makes the world better.
You stated that "The purpose of education is development of the person because when a person is taught, they can associate their knowledge with everything else". This would be true is the education system wasn't trying to turn humans into robots. Paolo Freire stated in the Pedagogy of the Oppressed, "Education thus becomes an act of depositing, in which the students are the depositories and the teacher is the depositor. Instead of communicating, the teacher issues communiqu"s and makes deposits which the students patiently receive, memorize, and repeat." At school, the things we are "taught" does not helps us develop because we in fact aren't being taught anything, we are memorizing things and because of that, we have knowledge of nothing and how can we develop if we no nothing.