Sounds like you’ve fallen for some farmer rhetoric.. How is growning crops to feed 28 million pigs to 6 million people? We’d have to eat 5 pigs each.. If it was really about food security, we’d surely plant crops to eat ourselves, which is much more efficient in terms of calorie per m^2.

Meat has many more negative externalities than plants. Thats the argument for substituting green farming.

Of course it’s political.. anything is to some degree.

Because of animals we grow far more grain than we need, giving us a substantial amount of necessary slack. If there is a wide spread crop failure, the price of grain rises, causing ranchers to sell breeding stock they can no longer afford to feed. Then humans then eat the grain instead of the animals.