Nobody serious has said that for half a century. Just a few of the less perceptive or more delusional members of the National Party.
However, the converse, that we should artificially restrict population growth, is also silly.
Indeed.
I am generally pro-immigration. But I have more reservations able guest workers than I do about regular immigrants. It seems to me that with that the country gets the benefit without the responsibility, and so creates a group of second class people that don't get full rights. You want immigrants to fill jobs, get people who will become citizens over time.
I agree. You want people who are interested in the country's future, who are emotionally invested in the country and call it home. Creating an underclass of foreign guest workers is a recipe for social unrest, and feeds xenophobes.