1) We can totaly live 100% without carbs. I'm not saying this is ideal, just that they are not essential.
2) Veggies are very low in carbs (excluding potatoes and the like). If you take the carbs in veggies in consideration, then we would need to take into consideration the tiny amounts of antimicrobals compounds they also have. You would need to eat many pounds of broccoli before you get as much carbs as in a few buckwheat pancakes.