For the most part, you throw seeds onto barren land and the magic happens.

Uh... no. As someone who has actually grown plants myself for food this is not accurate. Agriculture is hard. Soil nutritional content, acidity levels, too much or too little water depending on the plant, temperature and planting times matter, amount of sun varies by plant, some plants can be grown together and some cant, pests are a huge problem and need to be managed properly, etc. I really do encourage you to get some experience growing your own food from seed if you have the land to try it out available. It's 100% viable to do, but it's not nearly as simple as you made it sound there. Tonight part of my dinner will be a butternut squash I grew myself. It's quite fufilling.

A great example of how complex and fragile our agriculture currently is: That Haber-Bosch Process I mentioned? 40% of Global calories are made possible by it is the typical estimate. It's part of the Natural Gas -> Fertilizer supply chain.