Sure, and now compare polities which manage to keep defection to a minimum or structure the process of "defecting" to serve the polities purpose instead of being truly adversarial. Bruce Bueno de Mesquitas "the logic of political survival" and various works by daron acemogolu have the data on how much better these polities do.

If there's no pure play dominant strategy, you will always get a fraction of defectors willing to try their luck. But coopération still emerges, and the polities that manage to cooperate more still tend to survive and thrive more.