The decay and destruction of their infrastructure was basically a foregone conclusion when we started the wars. Without our intervention and continued presence the damage would have been much higher. This in no way excuses or justifies us starting the conflicts to begin with, but, our rules of engagement are very strict and err heavily in favor of preventing civilian casualties, too a fault, many soldiers would say. This also means minimizing. Look at the battle of Ramadi. We /definitely/ won there. Then we lost it, and won it back. So it is quite possible to win these wars, but they require advanced warfare skills at a tactical and strategical level and the political will to not back out. We only last Ramadi because of politics.