Well I think there are a lot of people out there who define bullying as "when a random person in a group is selected to be harassed". And if you ask them what they think about it they would say "It's horrible and totally unacceptable".
But "disciplining" someone that is acting weird on the other hand is the right thing to do, that is not "bullying" to them. But for the person that becomes the subject of this it becomes, "you sit wrong", "you talk wrong", "you eat wrong", "your sense of humor is wrong" until it feels like you can't do anything right. Some people even think they can fix your "wrong" behavior by hitting you, and then it becomes physical bullying.
A lot of people wanna believe that bullying is like the fist scenario because that is easier than actually having to start accepting people the way they are - even if they are a little "weird".