Do political endorsements by newspapers have much impact? It was debatable even back in the 1980s, when daily circulation stood at about 63 million nationwide, and it’s even more uncertain now that the number has dropped by more than half. But while some people study polls, I watch editorial pages for insight about this vexing Democratic presidential race.

Pete Buttigieg had not received a single endorsement from a daily newspaper until a few days ago when he picked up backing of the San Di...