As I believe I pointed out, the details are multiple, complex and not easily argued outside of formal models. But the facts are simple. If you allow your people to buy, what others produce, then the others develop. The US stepped up to the plate, when it was unspeakably wealthy and the Europeans thrived. In the 1970s the Europeans should have started doing the same, but instead could not develop into developed economies and preferred to continue the leeching on the American "development program" that had bootstrapped them out of poverty. This was extremely expensive for the US, but much worse for the developed countries as it siphoned off buying power.
The US stepped up to the plate? The US made a fortune IMHO from the world having to buy all products from the US. There may have been a level of just wanting to help out Europe. But let's face facts, the US was the only nation in the world with production capacity. The UK spent all their money and energy fighting the Germans and they were bombed a good deal.
France was bombed to hell/fought to hell, Belgium was also, the Netherlands the same, Germany bombed to hell, Poland Russian, all of the East block Russian, Austria destroyed, Italy the same, Spain was a dictatorship, etc. etc. etc.
The US stepped up to the plate because they were the only one who could produce stuff, had ample raw materials, etc. And let's not fool ourselves, US companies did not loose money on those deals. And I am sorry, but in the 70's the EU economy was doing well (until the oil crisis) and was even overheating.
But the problem for the US and their dwindling exports was that US companies went to Europe and started producing there for the local market, other companies exported jobs to low income countries. This is a very complex issue but it starts with over consumption IMHO, the US gobbles up too much of everything. Most other countries do not have horrendous product warehouses, they have supermarkets and other huge outlets.
Over consumption combined with lack of production is what led to the US trade deficit. Not what the EU did but what the US did. The trade balance between the EU and the United States in 2014 was 94 billion negative (US imported more than it exported) but that is a drop in the sea compared to the 505 billion that the US had as a trade deficit that year. The trade deficit with China that year was 324.6 billion. And that is the real problem. Not the EU, sure it would be nice if it were a bit more balanced but the US exports mostly services to Europe and that will never get you a full trade balance because anything that the US produces mostly is consumed in the US (which is totally fine by me, but it does lead to trade imbalances).