The problem is not unemployment, it is raising the bar for valuable labor. Arguably the standard of living has already declined for the average human individual. A factory job used to afford a single worker with modest education a house and a family. That said, generative AI will have far less impact here than, say, a robot arm.
That seems like a different (and real, but modern) problem compared to "we never would have left subsistence farming without a massive unemployment period (painful job loss) brought about by new technology" the the OP suggested.
