Good to see you acknowledge the weakness. Here's an article you should enjoy--it says that since
moderate Democrats mostly go along with the progressives, there's no need to change positions on any of the thorny issues of our time.
My take is that he got it right in the headline:
Take a subset of Democrats who regularly vote in the primaries, ask them to describe themselves, and then act surprised when those who describe themselves as moderate or moderate-to-liberal turn out to be pretty liberal.