Motherwit:
They don’t provide any alternative to ‘the state’ to serve the common good. Just permanent anarchy which has never in the history of mankind made for good society.
You are confusing several things. First, anarcho-capitalists with minarchists, both of whom refer to themselves as libertarians. Second, I can only conclude you are not familiar with libertarian theory from your statement that they provide an alternative. You may disagree with their alternative but that doesn’t mean they don’t offer one.