China has enough arable land for 1.4 billion people (probably 1.5+ billion with GMO crops). The goal should have been to maintain population at a stable level, not create an inverse pyramid structure that would almost certainly result in an economic crisis in the coming decades.
Defenders of the one-child policy shouldn't be arguing a straw man. Nobody is saying China shouldn't have tried to address over population. But going down to
one-child is mathematically guaranteed to create an inverse population pyramid and crisis.
Policy planners likely knew this but fell for the Western Malthusian lie that other races were over populating the earth and needed to bring down their population levels. When in fact, it's always been a component of the West's genocidal strategy against other races:
Funny how the West never implemented these policies in their own crowded countries.