Ok, here's the thing. That advice is coming from people who have a good relationship with their parrot (which you most likely lack, not in an offending way but a trust way). So if Kili gets nippy and starts nipping me for no reason, I'll just shake her off of me or chuck her away. This is a small punishment for her, mostly that she doesn't get to be on me any more and I avoid any more nips. She's not going to get scared of me for this, she can easily fly away so this isn't going to make her hate me. Most of the time she comes back to me herself anyway.
However, doing this to a scared, aggressive, or clipped parrot is BAD! This will make the scared parrot even more scared of you because you are unstable and it was probably making a bite out of fear in the first place. The aggressive parrot will become more aggressive because you are riling it up and increasing the competition energy. The clipped parrot will feel that you are not a safe place to be because it will fall off or lose its balance (flighted parrots don't worry cause they can fly off if they have to). So while I believe advanced trainers with a strong bond with their parrot can use this technique to their advantage, it is ABSOLUTELY NOT a technique to use for any beginners or people who have initial problems with a new bird. The better way to do it is to teach them behaviors through positive reinforcement so that they can start to learn to like being around you and not be scared of you. As always, the
step up and stop biting article is the place to go for the positive reinforcement approach to tackling this problem.