There's a difference between "noob" as an insult and "noob" as a identifier. The ad is aimed specifically at people who have never played before -- i.e. noobs, by gaming definition. Using it in-game is, 90% of the time, intended as an insulting commentary on someone's in-game play.
"That was a noob mistake I made there" is fine, as is saying "sorry about my friend top lane. He's a noob and is learning the lane"...provided your friend is a new player or new to the lane, but don't use it in an insulting fashion. That's the key difference -- most times players use the term they're using it as an insult.