Extreme 2 is also a cherry picked fear-mongering exampleThat's right. It was supposed to be. As the name implies, it's an EXTREME example. What I mean is, the opposite of fully closed borders are fully open borders. No verifications whatsoever, of any kind. And of course, this is meant to be a ridicule example. Just extreme ends of a wide spectrum.
If we loosened immigration restrictions, the undocumented immigrants would be replaced with legal and documented immigrants........ Also, I believe that all welfare should be abolishedWhat you're talking here, is a moderate solution, so it's a completely different topic.
If we wanna talk about the RIGHT solution, then.... Personally I believe in meritocracy. Just calculating what is "best". To decide if a country needs more open or more closed borders. Based on circumstances and "realpolitik".
https://en.wikipedia.org/wiki/Realpolitik