This is a huge distinction I want to point out: Nothing anyone has done in the past twenty years has been to make advertising more effective, though that is what is often claimed. The system however, only works towards making advertising more profitable to Google and Facebook. Everything else, including advertising effectiveness, has been slaughtered at the altar of "Gotta make line go up" inside Google and Facebook.

Both companies benefit greatly if the amount you spend on advertising goes up because it's not as effective as it used to be.

They also run most advertising as explicitly adversarial instant auctions, meaning the ad that runs before your Youtube video isn't the one most likely to get you what you want, or fix a problem you have, or even please your dopamine system, but rather the ad you see is primarily driven by who spends the most. This means that every midsized company that is so stupid as to misconfigure their advertising run will run a lot of ineffective ads, while the lean company doing innovative things locally who can only afford a "reasonable" ad spend will end up running far fewer ads.

The system empowers those with deep pockets and silences those without. Intentionally. This also makes it pretty easy to keep your new competition from getting any oxygen in a market.

I believe Google says that they include other things in the bidding process, including a specific claim that if you run a shitty ad that nobody every clicks on, it will be down-ranked in the ad auction, but they have billions and billions of reasons to not do that as effectively as they could. They are financially motivated to make advertising less effective and more expensive for consumers and producers alike.