Who gives a shit about a hundred and fifty years ago, dude? Do you want to live in a society like the one from 1875?

You're the one who made the implicit assertion that immigration controls were a necessary condition for statehood, an assertion that is utterly untenable in face of even the most cursory knowledge of the history of immigration laws in the US or very nearly everywhere else.

What country in the world is going to let you just walk into their nation?

What's that got to do with anything? Is does not imply ought, in my day they covered this shit in high school.

You think all the countries in the world are fascist?

I think their governance structures incorporate elements of fascism, yes.

I don't see why the modern world makes immigration controls any *more* necessary for statehood than they were 150 years ago.

If states could defend their independence and enforce their laws internally with the much more limited admin and coercive capacity they had then, surely they can do so just as well now. If you have an argument otherwise, please make it.