I don't think this will answer your question but I'd like to believe (maybe I'm naive) that democrats go into this with mostly good intentions, honestly thinking that their policies will work to address the very problems they are designed for - helping the poor, income and wealth inequality, the environment, homelessness, crime, etc. And, many of their policies, if you don't analyze them, sound good on paper. But, they have two main troubles:
1. They don't really fully analyze what they want to do before they do it. If it sounds good, just do it because if it sounds good it can't possibly fail.
2. When their policies backfire they don't own up to it and learn. They just automatically assume that their policies cant' fail so they figure the only reason they don't work is because they didn't do enough of what didn't work so they wind up doing more of what doesn't work. And, they never learn because they can't possibly fathom that their policies to help people don't work because policies designed to help people can't possibly fail.
So, I don't know if that means they are totally incompetent or just plain stupid. But, it is in their genetics. It is a genetic disease but the only cure would be gene therapy. But, like being an alcholic, you have to first admit you have a problem first in order to see that you need gene therapy. Right now they can't see that they have a problem.