The New York dinner is used as a way to signal publicly that politicians in our democracy are temporary adversaries, not permanent enemies, and that leaders have shared values that help hold the system together.
Ever since the first dinner in 1945, nearly every presidential candidate has attended the white-tie formal event at the swanky Waldorf-Astoria Hotel. It's named after Al Smith, the beloved four-term Democratic governor of New York who was the state's first Catholic governor and the first candidate of that faith to run as a major-party presidential nominee.
The official purpose of the dinner is to raise money to help poor families in the Catholic Archdiocese of New York -- this year's dinner raised a record $6 million -- and show that the commitment to charity transcends the politics of the moment.
"I never suggest that the press is biased," Romney said then. "I recognize they have their job to do and I have my job to do. My job is to lay out a positive vision for the future of the country. And their job is to make sure no one else finds out about it."
Obama told a similar gag: "Earlier today, I went shopping at some stores in Midtown. I understand Gov. Romney went shopping for some stores in Midtown."
That was a world away from the caustic humor Trump and Clinton resorted to, which actually drew some boos.
Things went sour when Trump called Clinton "so corrupt," and continued, "Here she is in public, pretending not to hate Catholics." Audience members began jeering.
When Clinton got to the podium, she took a few tough shots of her own. "After listening to your speech, I will also enjoy listening to (Trump's running mate) Mike Pence deny you ever made it," Clinton said.
"I'm surprised I'm up here at all," Clinton said at one point. "I didn't think he'd be OK with a peaceful transition of power."
It was a lost opportunity for both candidates to show they are more than just political gladiators, constantly thirsting for more combat. Come January, when the next president takes office and starts the difficult, thankless task of building alliances and getting laws passed, he or she may look back at the Al Smith dinner wistfully, as a wasted chance to start healing a bitterly divided nation.