What, according to O’Brien, are the benefits of stories?

In The Things They Carried, Tim O'Brien presents a linked series of stories about his experiences in the Vietnam War. However, he does not limit his perspective to actual combat but also writes of his life leading up to the war and the war's effect upon him as an older writer, long after the war is over.
Several chapters talk about the value and veracity of war stories. For instance, in the chapter "How to Tell a True War Story," O'Brien makes it clear that real war stories are so bizarre that they are all but unbelievable. He emphasizes that there are never morals such as Hollywood likes to invent in true war stories.

A true war story is never moral. It does not instruct, nor encourage virtue, nor suggest models of proper human behavior, nor restrain men from doing the things men have always done. If a story seems moral, do not believe it.

O'Brien clarifies that true war stories are incredible, obscene, embarrassing, crazy, and contradictory. Real war stories don't generalize or indulge in abstractions such as "War is hell." Often, in war stories, there is no point.
In the chapter "Good Form," O'Brien explains further what stories mean to him. He says that in writing this book: "I invent myself." He says that sometimes truth in stories is truer than events as they really happened. He adds that writing the stories enables him to look at things that he is otherwise unable to look at.
O'Brien explains the greatest benefit of stories, however, in the last chapter called "The Lives of the Dead." In this chapter, he writes not only about dead soldiers in Vietnam but also the death of his childhood sweetheart, Linda. He begins by stating that "stories can save us." He says that writing about people in stories brings their memories back to life. He writes:

The thing about a story is that you dream it as you tell it, hoping that others might dream along with you, and in this way memory and imagination and language combine to make spirits in the head. There is the illusion of aliveness.

As O'Brien describes Linda's death by brain tumor at nine years old, he says that as a writer he wants to "save Linda's life. Not her body—her life." In other words, writing about her in a story causes him to remember her, which somehow brings her back to life in a dreamlike sense. O'Brien summarizes his viewpoint by saying that in Vietnam, "We kept the dead alive with stories." However, it is not for their sake, but for the sake of the living. As O'Brien clarifies in the last line of the book: "I realize it is as Tim trying to save Timmy's life with a story."