Who said anything about a lawn? [Edit. And no, not certainly. It would be better for you to procure your food from someone who grows it efficiently. Being /good/ at growing food without waste is fucking hard, leave it to the experts. Now, if you are not looking at this purely from an efficiency standpoint, then things like aesthetics, mental well being etc. come into play and you should do whatever floats your boat]
The experts you speak of tend to just be simply putting enormous amounts of petroleum and chemicals and capital toward producing kilocalories. In the process they strip the ground of nutrients and deplete topsoil.
And we likely both agree that continuing to improve those processes is worthwhile and critical. There is plenty to be left desired with modern farming - lack of variety, agriculture as IP, flat taste, etc... but this talk of "home-farming" as a solution to the bigger problems is foolish. I'm not saying don't grow a garden. I have a garden with fresh vegetables, and I love it, but I'm under no illusion that it is a solution to any other problem than my desire for fresh veggies.