People don't exist in their bubbles, that's the problem.
Say you have a libertarian society where no consensus can be made and everyone just makes independent choices and agrees to follow the NAP.
Now let's say one warlord makes a group which does not follow the NAP, and they decide to raid and steal everyone's property. The risk for them is very high, as well as the reward.
This libertarian society cannot defend itself against that, because if that warlord has more weapons and influence, he can easily take the property of many isolated individuals.
They don't make choices democratically or autocratically, meaning that no cohesive defence can be drafted against this warlord.
The only defence against this is if you have one very wealthy person who funds a paid military to protect his property, and in return starts offering protection services to others in return for a fee. Well now you're back to a state again, because this is no different from taxation done by an autocrat.