Because they could improve your life. To come up with good examples, one would have to know more about your preferences.

But imagine there's an event (party, fair, game jam) and the only way to know it's happening is to specifically search for it, there are no posters or advertisements online. Don't you think that some people that would have wanted to go would miss it because they never even noticed that there was an event?

> one would have to know more about your preferences

And creepy/stalking advertisers grab all they can learn about my preferences. That's the state of ads on the internet for the past 20 years and I have never seen it "advertised" (haha) as a good thing.

Let me give you an example: I don't mind raking leaves, but I hate the step where you have to use the rake in one hand and your hand in the other to pick them up, spilling leaves on the trail to the bin.

My wife saw an ad for "rake hands" -- I had never thought that a solution to my gripe would exist, but for twenty bucks a significant source of friction in my yard work is gone, and I would have never even thought to look for such a solution.

I think the answer is obvious, no? Because there may be products that can make your life better but you don't know about them. It's a bit like asking "why would you ever want a medical treatment you didn't know existed?" Because I, not being a doctor, don't know of the existence of most medical treatments but some may be able to cure diseases or other ailments I have.

> why would you ever want a medical treatment you didn't know existed

That's the American spirit! As a European, it terrifies me that anyone would want to give advice to a doctor.