That's because they push ads at people for what they think they want. That's very different from people buying ads for what those people actually want.
For example, I buy hot rod magazines for ads for cool stuff for my car. I'm not interested in furniture ads in those magazines, and furniture makers don't advertise in car mags. When I want to buy furniture, then I'll buy a home decor magazine and look at furniture ads. I don't want to see a fuel injection pump in a home decor magazine.
Hemmings Motor News is another example of effective advertising. It's nothing but car ads - and people pay for a subscription.
An online example is newegg.com. All it is is computer electronics. It's my go-to location when I'm looking for stuff for my computer. Seeing ads on newegg is exactly why I'm going there.
I tend to watch youtube videos about cars. One day, the absurdity struck me - they're trying to force me to watch ads at the beginning, but the whole video is basically an ad. It's absolutely ridiculous, the idea that I need to watch an ad for something I'm not interested in to "pay" for watching an ad for something I am interested in (albeit I'm probably going to buy neither in the near future).
Of course, if I actually was able to buttonhole some guru at Google who understood the business and my situation, they would just look at me like I was an idiot and say "we warned you that if you turned off the various personalization features the ads wouldn't be relevant".
But if I left every option turned on, the ads wouldn't be better, just creepier.
For example, I buy hot rod magazines for ads for cool stuff for my car. I'm not interested in furniture ads in those magazines, and furniture makers don't advertise in car mags. When I want to buy furniture, then I'll buy a home decor magazine and look at furniture ads. I don't want to see a fuel injection pump in a home decor magazine.
Hemmings Motor News is another example of effective advertising. It's nothing but car ads - and people pay for a subscription.
An online example is newegg.com. All it is is computer electronics. It's my go-to location when I'm looking for stuff for my computer. Seeing ads on newegg is exactly why I'm going there.