Humans have been doing agriculture for 10's of 1000's of years. Simply stating, "Well, that just has to go, period." without explanation (and then moving on from there) is cute, and ridiculous.
We're basically tapped out in terms of arable land usage; you should look at the numbers some time, they are alarming (I recommend the FAO's "Livestock's Long Shadow"). Meanwhile, the energy budget of the planet exceeds by many orders of magnitude what is required to satisfy the meager energy needs of humans. What we need to do is stop dispersing our energy consumption through soil, plant matter, cow intestines, etc., before it gets to humans.
