The NAP can’t work to prevent aggression in and of itself.
A lawful authority is needed so that everyone is clear on what actions do & do not constitute aggression.
Without it folks would take it upon themselves to make that determination.
Peter believes abortion constitutes aggression, Paul doesn’t.
Peter believes intellectual property can be stolen (via aggression) while Paul doesn’t believe it’s property at all.
Do you see the problem? Those are just two examples that libertarians disagree on. Now factor in the billions of people whose views aren’t remotely libertarian: Commies, Socialists, NeoCons, Jihadists etc.
Nobody has argued that there should not be lawful organizations or rules. They should be based on ISO and not the whims of politicians. You need to do more research and reading regarding Voluntaryist philosophy, as your criticisms do not even apply to the philosophy you are attempting to question.
You can’t have competition in law & protect rights.
If you believe that you can you need to do more thinking