It is interesting seeing how hard this assertion is being pushed in some area for political purposes. Especially as it counters another message coming from the same groups. I am not sure how the two can be reconciled. (note: I am neither advocating or criticising the below)

1. We need mass immigration to keep up growth

2. Robots and AI are coming to take our jobs, so get used to it.

Many in politics, think-tanks and media sphere seem to be pushing both quite heavily, especially 2. Both are being memed into public consciousness, but by who and for what purpose I don't know.

I have not thought it all through, but surely if you are expecting higher unemployment supported by a welfare state you would want a smaller population? Both present a (perceived or real) threat in the minds of the working class and a somewhat contradictory message. It is easy to adopt a conspiratorial mindset on this in the belief that the public are being groomed for mass unemployment and to accept further exacerbated social inequality.