> Their primary purpose is to prevent lethal intergroup violence and blood feuds.

A state's primary purpose is to maintain a territorial monopoly on legitimate violence and to secure its continued existence. Generally this is at odds with its founding myth, but it's pretty obvious that states are also subject to a process that resembles evolution by natural selection. That said, I'm not even aware of any notable state or state-like entity that was created with the goal of "ending blood feuds". The vast majority of these territorial monopolies were created by means of conquest where the goal was to acquire resources owned by the people in some territory or with the goal of pooling resources to defend against such conquest.