Border have to exist to some degree, simply from a management perspective. Even if we threw all state and country borders away, it'd be literally impossible for a single government to effectively govern the world. You'd need to divide it all up into smaller regions to be managed. Otherwise, we'd might as well just fall back into the pre-industrial age as infrastructure erodes due to poor governmental oversight and management.
This has so completely disappeared from discourse over the past four years. I remember when it used to be that "building the wall" was stupid at best and bigoted at worst. But now, it's all, "Of course we agree that we need a strong border, but we're the ones who will actually do it, Trump's all talk."
It's always the Republicans that get to set which values and goals the country persues, while the Democrats just run on pragmatism and efficiency. It's like they're allergic to making moral claims.
"Yeah, but proceeds to present an argument that completely ignores the underlying premise that everyone should be cool with all being one planet helping each other instead of returning to squabbling tribal mentality of 'us vs them' and 'if I give themsomethen I'll haveless' and people need to stop letting conflicts of our parents and great-great-great-x147-grandparents started decide how we view our neighbors"
I'm pretty sure neoliberals also actually advocate for open borders and reduced immigration in general, and often accuse the left of being anti-immigration because of concerns regarding wages by unions.