American outsiders and the short story

Jim Shepherd, whom I don't know a lot about - hasn't he written stories on baseball, including one that was quite good but kind of a retake on a great SI story about Don Hoak facing Fidel Castro in a Cuban baseball game that any baseball nut of my age probably remembers reading as a kid? - has a story, Boys Town, in the current New Yorker - one of the best they've run this year, I think. It's in that very American genre of first person life story by a guy who's over the edge, as we become increasingly aware as the story progresses and his actions become more and more strange and antisocial. This story falls within the orbit of TC Boyle, George Saunders, Joyce Carol Oates, and a slew of others. Very well written, very disturbing, totally credible. Why are these outsiders so important to American fiction? There's the old trope, probably valid, that English fiction about getting the protagonist to join society (Fielding to Austen to Dickens to Forster ... ) and American fiction as been about breaking the protagonist free from society (Hawthorne to Melville to Twain to Hemingway to Ellison to Kerouac and so on). This American outsider tendency is even a stronger strain in the short story, in that there's a related, probably true, trope that novels are about fits and stories are about misfits - can the misfit truly be sustained over the course of a whole novel? Rarely successfully. (Confederacy of Dunces may be one instance.) The misfit usually wears out his or her welcome in a short span, and the story may be the perfect format for the true and complete social outcast. (I've found this to be true in my own writing - stories are full of losers, sad and lonely folks, whom I would not want to put through the trauma of life in a novel.)