At the same time it is also a huge bubble, that Google is just hoping will never burst. People and businesses way overestimate the impact their ads are having and way underestimate the impact, that treating customers well can have.
Also, if your established it probably a good idea not to let new competitors get a foot hold in the market with an easy google win.
It's also pretty effective for local businesses because not a lot of local businesses are tech savvy enough use it effectively.