Context (which is basically what you're referring to) is just one strategy. Often, targeting is used to narrow in on an audience. Let's say I have a product t

Context (which is basically what you're referring to) is just one strategy. Often, targeting is used to narrow in on an audience. Let's say I have a product to sell but I don't know my exact audience- I'd start a very broadly targeted campaign then see which types of people are responding to the ad. I would then narrow my targeting based on response. The broad targeting can lead to insights that I wouldn't have received if I had targeted a specific publisher.