That's true, and I generally dislike them, thus I run an ad blocker and some limits on JS. However I have a bit of a broader view on the topic. For one instance, we wouldn't have many of the things we have without the economic backbone of the internet - ads. Google Maps - No, E Mail services - No and many more as they are just to drive user engagement to serve more ads or to lock you into the rest of their ecosystems hence Android and iOS and their integrations with the services. However I don't mind at all some higher quality marketing like technical blogs with some real value + a plug for their service on how it solves the problem, and similar sponsored content. There is almost always to sides to both stories.