Cancer is a family of diseases sharing some common characteristics. Cancer cells abandon their normal cooperative role in a body, and instead start to replicate uncontrollably, engaging in complex behaviors not just to avoid getting killed off by immune system, but to actually convince the body to give them access to more and more resources.

Advertising as currently practiced shares these characteristics. It's a malignant mutation of an idea that efficient markets need a way to connect goods and services with people wanting to buy them. Limited to honestly informing people about what's available on the market, it can serve a crucial function in enabling trade. In the real world however, it's moved way past that role.

Real world advertising is not about informing, it's about convincing. Over time, it became increasingly manipulative and dishonest. It also became more effective. In the process, it grew to consume a significant amount of resources of every company on the planet. It infected every communication medium in existence, both digital and analog. It shapes every product and service you touch, and it affects your interactions with everyone who isn't your close friend or family member. Through all that, it actively destroys trust in people and institutions alike, and corrupts the decision-making process in any market transaction. It became a legitimized form of industrial-scale psychological abuse, and there's no way you can resist its impact.

The growth of advertising is fueled by the enormous waste it creates. In any somewhat saturated market - which, today, is most of them - any effort you spent on advertising serves primarily to counteract the combined advertising efforts of your competitors. The same results could be achieved if every market player limited themselves to just informing customers about their goods and services. This, unfortunately, is impossible for humanity, and so we end up with a zero-sum game instead (or really negative-sum, if you count the externalities). If you have competitors, you can't not participate.

Tallying up: uncontrolled growth? Check. Destructive consequences? Check. Hard to kill? Check. Co-opts resources? Check. Advertising has the characteristics of cancer.