With votes still being counted, Democrats last week may have picked up as many as 40 seats in the House of Representatives. That would be their biggest gain since the Watergate year of 1974, and naturally progressives are expressing satisfaction. “Make No Mistake, the Midterm Elections Were a Democratic Victory,” chortled the New Yorker. Apparently American democracy works—at least when Democrats win.

Yet it’s worth recalling that this wasn’t the view two years ago after Donald Trump’s unexpected victory. Then the cry was...