Then why, pray tell, are rising young executives in all kinds of "conservative" organizations and businesses preferentially recruited from schools on that list?

That may be true for a lot of businesses, but when I was in on a number of startups, and knew other people also doing them, it became unpleasantly clear that although an MBA looks good on the letterhead and impresses investors, most of them are royal screwups when it comes to the environment of a rapidly-growing, innovative company.

You could send my old boss screaming into the night if you suggested hiring a Harvard MBA, but I'm sure such people do fine in the right environment, like IBM or some large bank.