Agreed. The US was responsible for dismantling a lot of state institutions of smaller countries, but that doesn't make them the original source of the problem. They are only responding to it. And yet, people who sympathize with dystopian supports cry "WORLD POLICE" until they are the ones that need help from the West.
Plus, arguably, no Iraq war = no Arab Spring, sure, also no ISIS, but then no unification of Iraqi partisan sects against ISIS. If we could go back and do it again, is Iraq the right decision? It's really hard to say. Saddam was going to have to be removed eventually, undoubtedly, did it happen the right way? Who knows. Has a whole lot of blood been shed? You bet. Could it have been avoided? I don't know. Maybe it's better to be supporting a new Iraq against ISIS than supporting Iraqi rebels against Hussein. Tough call.
Either way, it's made nations realize they shouldn't wait for us to come in on the ground and do it ourselves - it's bad for everybody. It's a lot better for people to fight the war themselves with our support than wait for us to come and do it with the full force of the American military. Nation building is hard for outsiders, supporting internal nation builders is much easier.