I'm not sure this is much of a counterpoint. The Inca didn't have a centralized currency, but we really don't know whether they had private property or not, ho

I'm not sure this is much of a counterpoint. The Inca didn't have a centralized currency, but we really don't know whether they had private property or not, how disputes were handled, or so on. They also seem to have had civil wars, child sacrifice, and other violent traditions. That being said, many things are possible in groups with smaller populations, I've heard stories of large communes being fairly successful with up to several thousand people. However, at some point they tend to become too disorganized and break down, in one way or another. In contrast, the concepts of private property and trade have enabled our human family to grow to 7 Billion, and population growth is barely even slowing down yet. Civilization allows things to work on an entirely different scale by providing a somewhat standardized framework for our territorial disputes. This is also the most non-violent time in history by far, according to researchers, presumably due to the end of tribalism. So, for me personally, there would have to be extremely compelling arguments to even begin to argue against the utility of private property as a social and economic system.