Read this back to yourself, it is probably up there with the dumbest thing I have ever read another the the sky is green scenario from Bazza world.
Water is essential for survival, a huge part of our body is made up of water, we need water to hydrate if we get deprived of it but have everything else we will die in a relatively short time, we don't need carbs at any time, the body will quite happily live on proteins and fats, cut out all fats and metabolic function will suffer, cut out protein and see what happens. There are no benefits to carbs, there are no essential carbs, carbs are like someone else here already mentioned mere entertainment.
What multiple beneficial food groups are cut out?? And what exactly are these benefits you speak of??
Just because something has been manufactured and accepted as food does not make it essential and does not make it a food group.