Well, I agree that we are different, but we are made with same principals of nature as four legged animals. Both an elephant and horses are non-ruminant animals. Just like us they also digest foods with gut bacteria.
Point here was not to worry about protein needs as much as pushed in western part of the world, and give in to eating heavy meats and processed foods. Also we get protein from all living plants. No one suggested to eat grass.
I know most people give in because of fear of not having enough protein.