The far right are picking wedge issues not from principle, but from political expediency.
In the UK they've switched from attacking immigrants to attacking disability benefits, because the clampdown on immigration was effective (though they obviously are continuing to shout about immigration and immigrants).
So if the "open-door" immigration policy didn't exist, they would have picked something else as the wedge issue. They DGAF about immigration per se, it's just something that will rile up the base and get attention.
I think people want back to more historically normal levels of migration in general. Possibly less due to what one might consider an integration backlog due to rapid migration.
The illegal migration was an easy target for this since it's indeed the only thing some people are opposed to and it doesn't quite activate a big created class of people that have a migrant background.
In the UK they've switched from attacking immigrants to attacking disability benefits, because the clampdown on immigration was effective (though they obviously are continuing to shout about immigration and immigrants).
So if the "open-door" immigration policy didn't exist, they would have picked something else as the wedge issue. They DGAF about immigration per se, it's just something that will rile up the base and get attention.