How does Krakauer stating that he is not an impartial biographer affect the readers understanding of the story?

Krakauer's statement alerts the reader to the fact that much of Chris' story is enhanced by Krakauer's own experiences. Over the course of the novel, we come to see that Chris and Krakauer had a number of things in common..... things that might possible give Krakauer a greater insight into Chris' character.