Well, but just because we have encountered great librarians (us too) doesn't mean that this isn't being taught in library school these days. It may be part of the pedagogy for school librarians (I wouldn't think public librarians would get the same emphasis) because part of their role is seen as developing literacy, etc, and as we know, party line for teachers and educators in many cases is to keep kids reading at their level in educational contexts. The idea is presumably to avoid poor comprehension and discouragement.
