Farewell, Worst Minister

When Jacinda Ardern resigned as prime minister of New Zealand last month, she framed her decision in terms of natural human limitations. Politicians “give all that we can, for as long as we can, and then it’s time,” she said. Similarly, in stepping down as leader last week, Scotland’s first minister, Nicola Sturgeon, said she could no longer deliver everything her job “demands and deserves.”

It’s a nice idea: Politicians growing old gracefully, respecting the seasons of one’s career. Still, no amount of positive spin can gloss over a legacy mired...