However, it neglects to mention the one fatal flaw in the whole idea - a strong, pro-people, leftist economic platform would be opposed by corporate America and most wealthy individuals, they're the main source of soft money donations to the DNC, and the DNC values that money more than anything, including winning elections.
So it is a sound observarion and a worksble strategy, but can only succeed if those in the position to affect Democratic platforms would be willing to engage in it, and all indications are that they simply are not.