I think it helps to have it there because the term itself (CVV, CSC) is not very intuitive when compared to the other terminology associated with a credit card. For example, card number, expiration date, name on the card, etc.
Even though online shopping is more common these days, some people may not quite understand what CVV/CSV means at a quick glance. For example, I myself was familiar only with CVV code. CSC term was new to me when I read this question.
In fact, even the cards themselves don't have the security code labelled anywhere. I have a full 7 digit code on the back of my card and it doesn't say CVV or CSV. Besides, not all 7 of the qualify as the code, it's only the last 3. And clearly, each card has it implemented differently. AMEX has it in the front of the card and is 4 digits. You don't have any of these problems with the card number, expiration date, etc. because it's consistent across different vendors and is self explanatory.
So to make up for the inconsistency among different cards, I think it makes sense to help the user out by giving them quick tips to find out where to find the code.
My recommendation is either make the term more intention-revealing, for example, "Security Code" and/or leaving helpful hints in there that's not obtrusive.