The Federal Reserve's fundamental blunder in no way excuses the reckless, eye-popping practices of those mortgage bankers who lent money to people without even checking that their alleged incomes were real or who, in effect, gave the wink and nod to dicey borrowers, signaling that when their teaser interest rates were up, they could get new mortgages at new teaser rates.
Or to put it another way, it's not completely bonkers that the German government does not wish to - in effect - finance the lifestyles of Italians and Spanish people, without checking whether German voters think that's tickety-boo.