Have you never heard the term “state monopoly on violence”? The state (in the form of law enforcement officers) is the only entity permitted to employ violence to keep the peace.
Indeed, per the Widpedia article, Max Weber in his essay Politics as a Vocation (1919) stated that the monopoly on violence is the defining conception of the state.
If I have a dispute with my neighbor, I can’t legally use violence to resolve the dispute. That includes family feuds and duels.
If you lose the state, you lose this check, and you lose civilization. That’s why after the Roman Empire collapsed, Western Europe devolved into a bunch of warring tribes.