Were “Dean or bust” people blamed for Kerry loosing?

[Sumner 1868]

Some did, but the Dean coalition was different from the 2016 Sanders coalition in being far more upscale. Dean did miserably through 2003-2004 among working-class Democrats of all races, and many polls showed him weaker than Kerry against Bush. His voters were mostly the "latte liberal" crowd, many of whom later voted for Hillary over Sanders.