Comment by simiones

There's a huge difference between purely intellectual subjects, like organic chemistry and integrals, and the mix of emotional and intellectual depth of a novel. A lot of the meaning of literary works is built on top of shared human experiences, just like the meaning of integrals is built on top of more foundational math. However, we don't have any good way (and certainly make no effort in school) to teach this shared human experience to pre-teens and teens.

A good part of the value of some of these works basically comes from recalling similar feelings you felt in situations similar to the characters, maybe comparing your actions at such times to theirs, or the reactions of other people you knew, etc. It's simply not possible to experience this part of the work as a teen. Perhaps one of the clearest examples of this limitation is in Lolita - the nature of the relationship described, the power and life experience differential, the contrast with the reader's normal interactions with children - are impossible to be conveyed to or truly empathized with by teens.