Westerfeld shakes his fist at genre-bashing whippersnappers*, as in his smack-down of the Guardian's dumb dumb dumb review of Chabon's latest by Adam Mars-Jones. A sampling:
That’s right, young readers. About a million years ago, writing alternate history meant you could only change one thing: Confederacy wins, Ghandi hit by train, cheese not invented. And it was the singularity of this shift that proved how clever you were, by showing how many dinosaurs you could kill by stepping on one butterfly.
And yes, that’s still a perfectly glorious thing to do. But to assert that any book not hewing to this rule must be “flawed” is super-lame. Plus it means you probably haven’t read as many comic books as, say, Michael Frickin’ Chabon!
I think there's a novel in cheese not invented. (That sentence is rich with possible meanings.) Read Scott's whole post. He asks for your help disproving Mr. Mars-Jones' thesis in the comments.
*I have no idea who this guy is and whether he's a whippersnapper or, really, what a whippersnapper is beyond my grandmother's all-purpose term for a moron. (Okay, so really I did know, but wanted to use the word anyway. I'm slippery like that.)