It is an old, wrong concept that leads to failed foreign policy.
That is because imperialism, bullying, and control-freak domination is generally distasteful to every sane individual everywhere.
Take Adolf Hitler and his "Deutschland über alles", Dick Cheney and his tortured ideology, or current right wing religiosity as examples.
It is the opposite of the lyric that says "smile at me, I will understand, because that is something everyone everywhere does in the same language".
Exceptionalism, however, is a psychological impairment that works the same way, in that, everyone easily understands it when they see it in action, but unlike friendliness, exceptionalism leads to a bad experience in one form or another, from resentment to war.
There is little wonder, then, why MOMCOM promotes exceptionalism: it is the emotional and mental atmosphere she wants the citizenry to embrace, so that warmonger policies are easier to push through.
Exceptionalism is good for the war profiteer business, since it moves money from the public treasury into the bank accounts of the one percenters (1%), the rich über alles, who continue to plunder the middle class and poor.