San Francisco Democrats — who have produced some of the most left-wing politicians in America, and some of the most astonishing examples of poor “progressive” governance — want to move the party to the center. That, at least, is the claim made by some local party activists in the pages of Politico on Monday: Leaders of the local party argue the famously liberal city has, in recent years, exported one bad political idea after another, leading Democrats astray and ceding power in Washington to Donald Trump and the GOP. They cite “defund the police,” symbolic resolutions about foreign conflicts like...