I was not talking about home gardens. There you can burn the soil for a few years till it becomes a problem. I was talking about commercial farming for food production from a nation wide perspective. Anti-famine as you will.
If you doubt me take two observations on your own. Go check out commercial soil that has been farmed with hybrids and chemical fertilizers for years. Look at what happens to the soil. It has become desertified. Plant a seed in a pot of that soil and a pot of your home soil and water it and see the difference. Put cow manure on both. The soil from the commercial farm has no life in it, there are no natural bacteria to break the poop down to food for the plant. The poop will not degrade, it will just dry up and blow away. Note also that the seedlings will be quite different. The one from your soil will do much better.
A Hybrid seed is much faster growing and tries to produce more fruit from the same soil. It is hard to support Hybrid seeds in an Organic garden without intensive methods of composting and levels of fertilization that cannot be done on a large scale level.
Now for a second experiment. Plant two tomatoe plants in your garden, and do not fertilize either. One Hybrid and one a Heritage seed. Where in fertile soil the Hybrid will out preform a Heritage seed hands down, in normal soil the Heritage will equal or excel in production (depending on the base fertility) and this is more telling. At the end of the year, which soil is healthier? Just cut the tomatoes off at the root level and let those plots go to weeds. The WEEDS will be healthier in the Heritage spot simply because the soil has been degraded by the Hybrid's over feeding from the soil.
It is a real lesson on gardening. A serious gardener raises soil, the soil raises the garden. Hybrids eat more from the soil than can be replaced by a green off season crop. So over time your top soil level will slowly reduce itself until the soil will no longer support anything but weeds.
Because there has been a garden in that area since 1965.