Most people, if you describe a train of events to them, will tell you what the result would be. They can put those events together in their minds, and argue from them that something will come to pass. There are few people, however, who, if you told them a result, would be able to evolve from their own inner consciousness what the steps were which led up to that result.

That’s Arthur Conan Doyle, from A Study in Scarlet, and it applies to what novelists do too: not just describe events, but put “events together in their minds” and see what happens as those events play out.

One reason I tend to argue against people who say they have no time or inclination for fiction is reality: in the form of nonfiction, even narrative nonfiction, it imposes limits on the imagination in a story (which may be one reason why so many people, especially those writing memoirs, are inclined to make shit up to make the story better). Fiction removes the reality constraint, and instead imagination imposes its own necessary and proper restraints on imagination.

At times fiction also pokes at the problems posed by reality, as in Richard Russo’s novel Straight Man. A chair is the pretext for a major fight between a married couple, and the man is describing a scene to his father-in-law:

“When she wouldn’t get out of the way, I set the bag down and took her by the shoulders. . . . Then . . . I don’t know. She must have tripped over the bag. I heard a crash, and when I turned she was there on the floor. She’d fallen into . . .”
He stops, unable to continue.
“The chair,” I say.
He stares at me through moist, confused eyes. “No, the stereo cabinet.”
“Oh, sorry,” I say. I my writing workshop I’d have explained to my students why, for symmetry, in had to be the chair.

In fiction symbols can align neatly as they so often don’t outside of fiction. The “train of events” runs smoothly or unsmoothly on the writer’s tracks, or on “their own inner consciousness.” Not always to an interesting end, but to an end that shows things nonfiction, whatever its virtues, often doesn’t.