What is "newb"

I have always wondered why the word "newb" and it's variation has pratically become an insult? I remembered it WAS used to designate a person new to the game.

I don't know why some people feel insulted when they're called newb. To me it means nothing to be called a newb.

Like when you do something accidental in diablo like blocking the way in maggot, you get called newb... Or when you kill someone in a duel, they call you a newb while the term means someone new to the game.