There must be close to a billion people world-wide who want to emigrate to the U.S.A. We cannot take them all, period.
As to why Asians, as a group, tend to vote for the Democratic Party, I believe it has to do with where they settle within the U.S.
I was shocked to learn that this voting block votes liberal, because as a whole, they are very hard working individuals. It doesn’t make sense unless it is where they live and settle.