Writing, to Martin, was not an exercise in self-expression. While he wrote some fiction, non-fictional descriptions of reality were his fort . If a man has nothing to say, he has no business writing. This is just as true in non-fiction as in fiction. There are levels of experience fiction can reach that non-fiction can never reach.
Fiction is a higher art than non-fiction.
Martin is generally credited with being the forerunner of the non-fiction novel that Truman Capote and Norman Mailer popularized in books such as Capote's In Cold Blood. Martin, for all his dedication to getting the facts and telling the story faithfully, realized that objectivity had its limits. The writer could not hold up a mirror to individuals in a society and refine himself out of existence. A writer has to be selective. Complete objectivity is impossible.