For U.S Ancaps who claim to be pro-immigration except for a nebulous idea of “welfare”, where do you actually draw the line?

Many ancaps in this subreddit say they’re pro-immigration in theory, yet when it actually comes towards any idea of liberalizing the border or increasing immigration in any capacity, they hide behind a vague veneer of “I’ll allow it when they stop giving welfare to immigrants”.

I do recognize instances of specific terrible policy decisions, such as Argentina’s combination of free healthcare + open borders making people from neighboring countries use the free healthcare off of the native populations’ dime.

But by and large, I haven’t seen convincing arguments that the institutions or incentive structures of the U.S makes loosening immigrant restrictions a net negative. For instance, most legal residents of the U.S need to be here for 5 years before they qualify for things like Medicaid and SNAP.