When 2 parties have a dispute it can either be resolved through violence, threats of violence, or by agreeing to 3rd party arbitration.
A common objection to the libertarian anarchist framework is that people won't agree to unbiased arbitration, so disputes will be resolved with coercion.
Some will, some won't. The more prone to violence a given society is, the less peaceful resolutions there will be.
But what the objector usually ignores is in a society with an ultimate arbitrator (a state) disputes are resolved via overwhelming force all the time. This is commonly how police resolve disputes. Most interactions with an officer of the state carries with it the threat of being locked in a cage and being forced to comply.
And under a state, challenging the state's edicts is only allowed in state courts. So that cannot be said to be unbiased 3rd party arbitration.
If the fear is that some parties to a dispute will get their way through brute force, we shouldn't empower an entity which is virtually guaranteed to do so.
