Columnist Ron Hart totes up the reasons, including the following:
Part of Hillary's problem was her insistence on staying in the race against Obama after she was mathematically out of it. She felt that math was elitist, and because many Democrats are not good with numbers, she kept going. Unlike "American Idol," where Americans actually take their vote seriously and when you lose you have to go home immediately, the Democratic primary allows losers to linger and make life hard for those who beat you. And linger she did.