Advertising and Power
As most people will not want to see advertising by choice, advertisers need several kinds of power in order to be in a position to have an influence.
Force feeding advertising
A magazine or website consisting exclusively of ads will receive little interest. Advertisers need the power to force feed ads to people, and they buy that power from media (or other organizations that have ad space for sale). If media contain ads, people who are interested in the subject matter of the medium, are going to see the ads.
Media depend on advertising
Advertisers' money also gives them a powerful position to media. Media often rely on advertising to make money. That makes it hard for them to critisize a company that is buying advertising space on that medium's pages or airtime. Furthermore, how can media critisize advertising in general, for instance acknowledging that it can be disrespectful to people? You don't bite the hand that feeds you.
Power to influence
Then there's the power to influence people, influencing their toughts and feelings into buying particular products, influencing their lives.
Power
So advertising is, in fact, a lot about power. Power that is bought with money. Power that gives advertising an almost unassailable position. Power that enables advertising to be disrespectful to people in various degrees.
Who pays for the advertising?
Of course, companies pay for their own advertising. But it's good to keep in mind that when you buy an advertised product, you also pay for the advertisements. Advertising costs are part of the product price, along with manufacturing costs. It's not that these costs are negligible.