If advertising is a cancer on society, what is advertising? If someone blogs on their company's platform and this is submitted to HN, or there's a "we're hiring" post on HN, or someone replies to "who's hiring", is that an ad and therefore cancer on society? If I enrolled to an evening school which I heard about from a YouTube ad which clearly knew my interests (real story), is that cancer on society or, since I think it was valuable and did not directly contribute to urbanization and other issues, is this no longer an ad because if it were an ad it would have been cancer?