I suppose for the same reason classical fairy-tales do the same. My best guess would be some desire to relate the external world to internal experiences. It's

I suppose for the same reason classical fairy-tales do the same. My best guess would be some desire to relate the external world to internal experiences. It's also an important didactic method in pedagogy. You might call it a form of "Student-centered learning", where a significant effort is made to meet the student where they are. Their desires and experiences should guide them to understand the external world through themselves.