It used to be that you could live naturally on a vegan diet without supplementing. The soil provided the B12 we need. But current farming methods have ruined the top soil so now we have to supplement. It was a very natural way of eating, and our unnatural methods have made it necessary to supplement.
Some plants do die when they are harvested, but apples fall from the tree and it does not harm the tree. Just pick up the apple and eat it.
Plants naturally shed their fruit and go on for years producing more.