Your opinions of immigration is reasonable but It seems impossible to limit the number of immigrants . Because, there are millions of immigrant people out there . For that reason, any country cannot limit the immigration for sure.
It is possible to limit immigration, if a country is having tough rules. For example, you may not find a lot many of the illegal immigrants in countries such as Japan and South Korea. The reason is that these countries are not very tolerant of illegal immigrants. Even Western nations such as Australia and Denmark have managed to limit the number of immigrants.