But the new mayor’s political coalition also provides a clue as to why a comprehensive policy response may never actually be tried. In his primary upset, de Blasio enjoyed strong backing from the city’s college-educated upper middle class. He even did slightly better among voters making between $100,000 and $200,000 than he did among the poor.

In a way, this shows the potential breadth of populism’s appeal. But while upper-middle-class voters are happy to support higher taxes on 1 percenters — not least because they’re tired of trying to compete with them for schools and real estate — they don’t necessarily want a program that would require their own taxes to rise substantially.

And this is a problem for the populist left, because to build the kind of welfare state — European, Scandinavian — that seems to really level incomes, you need lots of tax dollars from the non-rich. Yet the current Democratic coalition has been built on a promise to never raise taxes on anyone making under $250,000 … or maybe $400,000 … or possibly $500,000, the threshold de Blasio chose.

That promise has made it safe for many well-off voters, in New York and elsewhere, to cast votes for liberal populism. But it’s also made it impossible for the populist war on inequality to ever actually be won.