As an example, a pest control company canvassed one of my friends' cul-de-sacs and essentially threatened to send all the pests into his house by poisoning them and repelling them from all the neighbors. If you have a pest problem exclusion is usually cheaper and better than poison or repellent. My wife paid for trapping and control on her house for years and then I went around over the course of a couple of weeks and closed the gaps in her siding that were added by telecommunications companies like Verizon and AT&T and Comcast over the years. Mysteriously the pest problem went away after that.
So it's not always the case that the product being advertised is a net positive. Often it's net neutral or net negative. But the advertiser sure wants you to do it anyway.
Customers often do not know that products or even product categories exist and need to be informed about them.