July 26, 2009:
It may seem intuitive to naive authors that narrative fiction "should" be structured linearly because this reflects the way readers experience reality and is therefore "natural".
But, it doesn't.
Linear narration abstracts from the web of overdetermination driving most real-life decisions. Any reader who's ever sketched a decision list with more than two or three determinants per column understands this in practice. Linear fiction simplifies by removing the knots of complicating determinants which make real life messy, as opposed to the tidiness of fiction.
Some fictional genres rely on just this tidiness to achieve satisfaction: detective stories like to tie up those loose ends at the conclusion.
To writers this may seem "natural" because they're used to it, that is, because it conforms to the literary ideology of Realism / Naturalism which was part of the background of the world they were born into.
Because it returns to the 19th Century.