I would hazard that most people across the globe believe that their countries are the greatest in the world, at least some of the time. Here is where Americans are different: We believe we are the greatest country all of the time. It would be unpatriotic ever to think otherwise! By extension, we need never look to any other country for examples or wisdom. So, we find ourselves the only country in the industrialized world without universal healthcare and paid maternity leave. In our arrogance, we refuse to assume the same responsibilities of the other "lesser" nations in the world. China must do something about its pollution, but we need not ratify the Kyoto Protocol. Other countries are "barbaric" and "uncivilized" for torturing Americans and Christians, but it is fine for the United State to torture foreigners and Muslims. We expect other countries to accept refugees, but we are returning child countries to Latin American countries in the grip of lethal civil unrest. We are appalled by the abandonment of female babies in China, but we question whether any American citizen should have any responsibility for the education or health care of any fellow citizen's child.
That's "American exceptionalism," an excuse for failing where other countries succeed. It is code for a belief that this country will somehow be contaminated, diluted, weakened if it becomes more like any other country on the planet. It's a nasty bit of jargon, branding anyone who acknowledges the superiority of another country in any particular as a sort of attitudinal traitor to America. It is patriotism perverted against America's own citizens as well as a pathetically thin cover for our global arrogance.
Politicians should just stop saying "American exceptionalism." It's a waste of the public's word comprehension. They should just plug their fingers in their ears like pouty five year olds and chant, "We're not listening! We're not listening! Nanananana!" Or perhaps the chant should be, "I'm more patriotic than you are! Nanananana!" Then maybe we could bribe them with ice cream just to shut up and let the rest of us get on with the business of improving our country.