The Greeks and the Romans and many others are fell, but they ruled for quite a long period of time before eventually falling. The examples of anarchist societies, in general, last no more than a few years tops, many only months. All forms of government or organization generally faily historically. It's like the quote about democracy from Churchill, "It has been said that democracy is the worst form of government except all the others that have been tried."
There are inherit flaws in all forms of government, but I feel like they have gotten somewhat better to all the historical ones that have come and gone.