Most of what passes for ‘socialism’ in the U.S. today is actually clientelism, the exchange of favors for political support. Based on the examples of Venezuela and Post-soviet Russia, that’s likely even worse.
The most plausible argument for mass immigration would be something like factor efficiency plus Tiebout competition. Labor mobility improves people’s lives in the short run by letting labor move to where it’s most productive, a straightforward implication of welfare economics. It also improves lives in the long run by letting . . .