Nick Denton:

"I finally understand why the Left has failed over the last two decades. It has stopped trying to persuade. [...] For the Left, or at least for my debating partner tonight, even the acknowledgment that people are self-interested is a fatal concession to the conservative worldview. For them, better the purity of an absolute moral stance, than the messy act of political persuasion. For the dogmatic Left, the goal is perfection, at the expense of progress."

Nick, that's by design. The act of selling is morally tainted for the left, so why would you even expect them to make the effort?