But, one overlooked point is that most vegetarians do not live on vegetables: their diet is full of processed foods...........they just exclude meat..........so they become unhealthy as a result.
One other point to consider (and I am not defending vegetarianism) is that whichever way you look at it, a strict vegetarian would eat vegetables/fruit; but, omnivores derive their meat from animals that feed on plants.
In other words, everyone receives their nutrition (either directly or indirectly) from plants.