Yes, I also disagree, cardboard. I have a 2 year old, whom I try to treat with respect. That means absolutely no smacking, and almost no yelling. I talk to him about why whatever he's doing wrong is bad... i.e., I reason with him - and he listens. I've been able to reason with him about things for many months. Children of ANY age can be reasoned with, quite successfully.
However, if you ever smack a child, you won't be able to reason with them, because the only reason children listen to reason is if they trust you. How on earth are they going to trust someone who hits them? I wouldn't. I would have resentment against anyone who abused me, emotionally or physically, and would undermine attempts at reason.
There's no reason why children should ever, ever, ever be hit.