"This behavior is quite common..." is very misleading. This specific behavior is not common. Scratching an itch does not equal using a tool to scratch an itch. Every animal I've seen in nature knows how to use external static objects to help them scratch somewhere they can't reach. Dogs cats, bears, pigs, cows... etc. I think my cats are very intelligent, I've seen them use the bristle brush attachment we have on the wall to scratch themselves. If I ever watched one of them pick up a fork with their mouth and orient it in a way to scratch their back I would absolutely lose my mind. These are not the same behaviors.