The question isn't that much "why don't we accept all travel visas" but "why don't we accept all immigrants".
People are talking about the "risk that they stay" like it's something bad to have too many immigrants. And it ended up like some common sense idea. But what if it's not?
Did California or New York suffer from getting people moving from all the "country side" state? Did the US suffer from their immigration waves when they had open borders, and all you needed to get in was a medical exam on Ellis Island?
I think there’s pretty common and clear data on why unlimited immigration is harmful to the receiving country [0] (tl;dr; lowers wages and increases costs for non-immigrants).
The question is whether it’s worth it for the obvious benefit to immigrants. So it may be a net benefit when factoring the improvements to people who immigrate in.
The US benefited greatly from open immigration 100+ years ago because they weren’t that great and there wasn’t much to lose. So it’s apples to oranges of open immigration then to open immigration now. Back then there were no government services and land was literally given out for free.
People are talking about the "risk that they stay" like it's something bad to have too many immigrants. And it ended up like some common sense idea. But what if it's not?
Did California or New York suffer from getting people moving from all the "country side" state? Did the US suffer from their immigration waves when they had open borders, and all you needed to get in was a medical exam on Ellis Island?