[aluren]

>Why shouldn't groups of individuals have self-determination including the power to limit who can enter their country?

Why shouldn't groups of individuals have self-determination including the power to marginalize any subgroup or wage wars to others? Because it is immoral no matter how many people agree with it. Not letting people fleeing other countries' misery, war or repressive regimes is immoral no matter how many ways one wants to spin it. There are all sorts of questions on the implementation of it but the basic question (should we abandon people to misery, war or political persecution) is pretty much answered from a moral point of view.

>Different groups make different decisions about how they want to run their government (which is a good thing).

Most 'groups' are run by a single dictator imposing theie view on the rest, and even modern democracies are subject to interferences such as disenfranchising, lobbying etc. There's little legitimizing to be had on 'self-determination' there.

>For example, if you didn't control who can live in your country, you'd never be able to have a generous social safety net.

Is there any evidence for this? I mean most rich countries have both open borders within the EU and their social safety nets seem to be doing pretty fine.

[refurb]

I mean most rich countries have both open borders within the EU and their social safety nets seem to be doing pretty fine.

This is clearly untrue. Open borders for other citizens of EU countries, yes, but hardly "open borders".