Population growth by itself does not reduce the need for agricultural work; in fact, it increases it because there are more mouths to feed. As agriculture became more efficient, though (through innovation). a smaller percentage of the population was needed to produce enough food for everyone. The surplus of labor in agriculture would thus have led to falling wages in that sector. It’s not really a question of whether there was “enough work,” but of how the work would have compared to what else was available in the cities, etc. No doubt some of the farmhands who moved to the cities but who liked farming could have stayed in the country had they been willing to work for free.
Certainly some people were hurt by industrialization, in the same way that some people in modern industries are hurt when a technological innovation makes the work they do redundant and they lose their jobs. But as Dr. Woods noted above, the debate on whether industrialization was good for society as a whole (in material terms) is just about over.