Actually, I think you're right. I was trying to do a thought experiment here. I guess I never saw the Democratic Party as really committed these ideals, anyway. That made me more ready to "surrender" it as force for the left or progressives, and just make it generic government.
It also seemed like the only way to get a majority or eventual supermajority so that any legislation could get done at all. In other words, we used to negotiate with conservatives called republicans. Now we'd have the same debates, but with conservatives called democrats.
But I also understand how we could look to the Democratic party as the necessary home for social justice action. I guess I never valued the party that much, but I can why you wouldn't want to lose an inch of hard-fought progress within it.