Advertising does affect everyone in the broad picture. Specific advertising campaigns don't affect everyone, though. Also, different people are affected by different approaches. What works for one set of people doesn't for another.

This is why there are a set of different approaches that have been shown to be effective (given names like "the bandwagon" -- which covers the group of people who can be swayed by convincing them that everyone else is into something). A comprehensive campaign will have different ads for the same thing, each using a different approach, to maximize the number of people they affect.

By the way, if you ever want a deep-dive into this stuff without actually taking college courses on it, my recommendation is to find a copy of guidelines provided to car dealerships. Those things are very comprehensive, unabashed, and to-the-point.