The first prerogative of any political community worthy of the name – and this would include a stateless anarcho-capitalistic community – is to distinguish between who is a member and who is not, and to establish standards for non-members to join (and those standards are not and cannot be “any warm body with a pulse” – unless you’re a progressive, that is, whose movement thrives on the basis of low-information throngs pulling levers on your behalf; see below).
“Open-borders” libertarianism is common but IMO insipidly moronic because it is self-defeating for this very reason; in almost every case it involves immigration of populations who will not support libertarian policies, anarchistic or otherwise. They usually think “we can at least work with the statists on this area of common ground,” but they have things exactly backwards and have, as I mentioned in another thread, taken themselves out behind the barn and shot themselves in the back of the head by supporting this failed project (failed from the PoV of advancing the libertarian/freedom cause). Only the progressive statists (both in America and Europe) have properly understood the political-ideological impact.
Libertarians and anarchists should *first* make a free/libertarian society, and then welcome those who want to share in that (and only those who want to share in that). Inviting as many indigent people into the existing welfare-state societies, who come because they are attracted to those existing welfare-state societies, for whatever reason, and then expecting those people to support dismantling them is. . .moronic. Predictably self-immolating.
*(This definitely includes a stateless anarcho-capitalist community; lets say an excentric billionare who happened to live in it wanted to change it to a stated society – perhaps because he wanted to be in charge. He pays a bunch of people to come into that anarchistic society, who he plans to be his minions for organizing that society into a state under his control, by any means necessary. IMO it would not be morally objectionable for the members of that community, if they learned of his aims, to prevent those people from entering it’s area, without waiting for him to initiate force first. Now, people say this can be done because private roads et al but IMO the members of the community could resist such a plan, even if the owner of the roads said to himself “I’m a businessman, if his guys pay the same toll to use my roads as anyone else does, I’m not interested in their political ideology.”)