> ALL our staple food crops and most non staples are genetically engineered by millennia of cultivation and selective breeding

And during the last 100 years, the yields for many types of plants have grown several _times_ because of modern selective breeding methods. Here's a nice graph for cereals: https://en.wikipedia.org/wiki/File:Index-of-cereal-productio...

So you want to go back hundreds of years and force people to live in hunger with frequent famines?

There are plenty of patent-free crops. So just plant them. And the patents eventually expire.