It's another race to the bottom.
Right now the US has a monopoly on intelligence. If you're super smart, capable, and can create a $1bln buisness, you're probably going to move to the US, and the visas help support that.
Other countries want at least some people to come too, so they offer the same visa programs.
If no country offered work visas, these skills wouldn't get concentrated, and that's probably the better extreme.