If not for overpopulation, why should anyone bother about increasing food production beyond what is needed?
You make the same mistake European explorers did when they judged certain peoples as imprudent for not stowing food for a rainy day.
Those Europeans had no understanding that before overpopulation, there was no need to store for a rainy day, because those people they encounterd had never known a time when nature failed to provide them.
All of their surrounding world was their natural larder.
Why bother about storing stuff which can spoil and sicken you--or which you must worry over to prevent raiding by animals and insects?
So long have you worn the albatross of civilization and overpopulation around your neck, that you make the unconcious assumption that things made a necessity by overpoplation, were things that always were.