And just to expand on the above, modern farming heavily exploits heterosis (1) for greatly improved yields and healthier crops, even when not using "GMO" crops.
This means that while seed saving is, strictly speaking, possible, it is uneconomical -- properly fully heterozygotic seeds coming from an organization dedicated to making them will yield so much more than the second generation descending from those seeds (or any other natural seed stock) that everyone will gladly pay for them.
This means that while seed saving is, strictly speaking, possible, it is uneconomical -- properly fully heterozygotic seeds coming from an organization dedicated to making them will yield so much more than the second generation descending from those seeds (or any other natural seed stock) that everyone will gladly pay for them.
(1) https://en.wikipedia.org/wiki/Heterosis