You know why that is? Corn subsidies. The corn grown and fed to livestock and used for fuel isn't corn you would want to eat off the cob. Corn is cheap, hence why it's in EVERYTHING; not just livestock feed but in most produces in the grocery store.
Humans can't survive on grain alone. Try it, you'll end up weak, blind, probably crazy, and eventually dead.
Farming ideally would be done like the Polyface farm does it. Rotating livestock, they actually build topsoil. And provide not only calories, but NUTRITION; you could live solely off what they grow/raise on their farm and no outside food. You could not live solely off a corn.
Why don't you read Lierre Keith's book before you write her off? She had done her homework, and her book cites all the sources she used. Or are you just threatened she might actually confront you with logic?
An animal eating soy doesn't directly mean I am eating soy (getting the estrogen-like affects from it, the blocking of memory and decision making in the brain, etc).. And I don't eat feedlot beef anyway, I buy grass-fed beef, and other livestock usually fed grass/hay (goat, lamb, etc.). Or I eat wild game meat, which yes, sometimes they get into the soybean fields; but that's only a couple months out of the year and not their sole diet.