Except that those cardinal rules of literary criticism are more or less pointless and arbitrary. It's like how the cardinal rules of certain types of astrology form a (mostly) internally consistent system, but so what? Neither astrology or literary criticism produce useful results, except by happenstance. No one system of either discipline is provably better than another, so it's ridiculous to draw a line at psychoanalyzing dead authors when everything else is built on a foundation of sand.

Teaching classical literary criticism techniques is probably as good a way as any to improve students' reading comprehension, critical thinking, and writing skills. But let's not pretend it has some deeper significance beyond being a pedagogical tool.