This isn't hard to figure out. Atrios gets mostly there in three paragraphs. But I would like to stress one thing that he doesn't really get all the way to saying. The missing but inevitable conclusion is "incrementalist" Democrats actually believe the status quo is the best of all possible worlds.
They really do believe in an insurance-driven health care system. They really do believe in austerity fiscal policies that punish the needy by shrinking the social safety net. They really do believe in privatized education. They really do believe in the union busting, benefits slashing, freelance based sharing-tech economy. They really do believe "broken windows" policing and gentrification is good for cities. They really do believe in massive state surveillance and bombing foreign peoples into Freedom.
If they had the slightest bit concern about any of this stuff, they wouldn't have spent the past 10 months shouting down and vilifying the dirty hippies mobilizing against it. That's what the entire primary has been about. What do Democrats believe in most? They believe that, if you aren't doing well in this best of all possible worlds, it's because you are a loser and really just need to STFU so they don't have to feel so bad.
The people in the mainstream money wing of the Democratic party are not stupid or ignorant. They are just on the wrong side. And they are on the wrong side on purpose because that's where their core values are.