In the event, on perhaps the single most important issue - climate change - President Trump found himself in a minority of one, not a leader but a discounted, ignored and opposed outlier.
Does any of this matter? Are Trump's travails any more than of personal significance to a President who is clearly struggling to meet the demands of his office? The answer has to be that, whatever else may be the consequences of the pricking of Trump's bubble, the US and the world may now have to get used to a new world order.
Far from "making America great again", the new President seems to have fast-tracked a significant decline in American influence.
Why and how did this happen? The change so evident in Hamburg must in part constitute a judgment made of Trump's perceived personal failings; no one is watched more carefully and judged more severely than an incoming American President.
It is no exaggeration to say that Trump is seen by his colleagues, on the strength (or perhaps that should be weakness) of his performance so far - first as candidate and then as new President - as simply not up to the job.
It is also an inevitable outcome of the policy positions that Trump has taken - on climate change, on trade, on NATO, on Islam, and on innumerable aspects of bilateral relations with countries like Russia, China, Turkey - all of which have been marked by isolationism and a lack of understanding of the issues involved.
Even what was presented as a successful demarche in Saudi Arabia led to a repeat performance of the classic American tragedy, the arming of a repressive regime so that it could better preserve its power against a democratic alternative.
Whatever the reasons, the world will now have to adapt to a new scenario, one where American leadership is not a given or part of the natural order. And just at the moment when the American helm is taken by an uncertain and inexperienced pilot, there are suddenly other vessels making waves, not least in the Pacific, and ready to sail into a power vacuum.
We in New Zealand might see ourselves as mere spectators or bystanders of this tilting of the balance. But if the cards are to be re-shuffled, the Pacific is likely to be one of the regions most directly affected by the way they fall.
Whatever complaints may have been made or unease felt over recent times at the extent of the American hegemony in our part of the world, we must surely conclude that, whatever our concerns and reservations, we have greater freedom, security and opportunity under American leadership than is likely to be the case with any of the likely alternatives.
For us, a weakened and incompetent American president would mean a newly uncertain and possibly more dangerous world. Let us hope that American domestic opinion recognises the dangers as well.