Wrong!!!!
Its about having the sense to be ethical. The .223 is a very effective round. But is IMO, unethical for use in deer hunting. It is too small, lacks weight and performance characteristics necessary to ethically kill a deer.
We owe our quarry the respect to use a proper sized caliber not less, again in my opinion, than a .24 caliber.
The killing ability of the .223 has been proved time and again.
It is an ethical question.
One that many states have decided for us, by mandating that no caliber smaller than X be used in the pursuit of wild game of a certain species.