A necessity or a need is a necessary condition for something else.
A need in Economics and particularly a consumer need is something needed to be consumed, a necessary condition for achieving higher utility. An advertisment as such creates a need artificially. If the advertisment was restricted absolutely in giving raw information about the good( product or service) and not presenting it as a good, presenting it as something that would make one happier, one might be indifferent in purchasing that good. In which case one can be sad( disutility, a cost) because they cannot purchase it.
As such is prohibiting advertisment( or at least restricting it to be purely informational, being boring and monotonous) in compliance with the harm principle?