One possible answer, specifically for novelists, is that through memoirs and novels (and all storytelling media, including the often maligned cinema, television and comic books) people can convey life lessons they've learned with enough richness and depth that real transfer of wisdom can take place.
Most people are poor at conveying their life experience to others.
The main things that people learn from life, rather than from being told are reading, aren't stored in verbal form. As a result, people generally don't think that they can be represented with words. As a general rule, as people get older, they become less disposed to construct new patterns out of words, and the patterns in their brains become more subtle and nuanced, and more divergent from the simple cliche verbal patterns that are typically exchanged as something like a carrier wave for the real primate communications that determine peoples actions. It takes, essentially, literary talent, to look at the world and construct a novel and precise description of what you see rather recognizing the closest stored pattern and outputting the most appropriate available cliche.