One answer, which shouldn’t be discounted, is that inveighing against the evils of deficits makes you sound responsible, at least to people who haven’t studied the issue or kept up with the state of economic research. That’s why I used to mock centrists and media figures who preached the need for austerity as Very Serious People. Indeed, to this day, billionaires with political ambitions imagine that dire warnings about debt prove their seriousness.

Beyond that, the push for austerity was always driven in large part by ulterior motives. Specifically, debt fears were used as an excuse to cut spending on social programs, and also as an excuse for hobbling the ambitions of center-left governments.

Here in the United States, Republicans went through the entire Obama era claiming to be deeply concerned about budget deficits, forcing the country into years of spending cuts that slowed economic recovery. The moment Donald Trump moved into the White House, all those supposed concerns vanished, vindicating those of us who argued from the beginning that Republicans who posed as deficit hawks were phonies.

This politically weaponized Keynesianism is, by the way, probably the main reason U.S. economic growth has been good (not great) over the past two years, even though the 2017 tax cut completely failed to deliver the promised surge in private investment: federal spending has been growing at a rate not seen since the early years of the past decade.

But why does this history matter? After all, at this point unemployment rates in both the United States and Europe are near or below pre-crisis levels. Maybe there was a lot of unnecessary pain along the way, but aren’t we O.K. now?

No, we aren’t. The austerity years left many lasting scars, especially on politics.

There are multiple explanations for the populist rage that has put democracy at risk across the Western world, but the side effects of austerity rank high on the list.

In Eastern Europe, white nationalist parties came to power after center-left governments alienated the working class by letting themselves be talked or bullied into austerity policies. In Britain, support for right-wing extremists is strongest in regions hit hardest by fiscal austerity. And would we have Trump if years of wrongheaded austerity hadn’t delayed economic recovery under Barack Obama?