Executives climbing the corporate ladder to the top seem to lose IQ the higher up they get.That might explain why John Deere's top corporate bosses have imposed an astonishingly stupid policy on America's farmers. For years, they've decreed that while a farmer "technically owns" a tractor or other John Deere product, the owner is prohibited from making any repairs when the machinery breaks down, stalls out, etc. Instead, owners must call an auth…