I think the key problem is that attention is the only currency that many children have access to.
Many many many kids have mobile devices now, along with tons of free time and a strong desire to play games. What they don't often have is access to a credit card to purchase games or do in-app purchases. I think that a big part of why so many games lean on ads is because it's essentially the main currency that kids have access to: their own time.
Not exactly answering your question here, but I shipped a mobile game worldwide about a year ago with both ads and ability to unlock whole game via purchase to unlock.
My ads are as unintrusive as I could implement (watching an ad via button press to unlock a level). So far I have seen mostly iOS users are willing to purchase the game while Android users will heavily lean towards watching an ad to unlock a level. From what I have read (and seen so far) it looks as though the way I'm implementing ads is going to be highly unprofitable
Additionally integrating ads in general was a huge pain in the ass. I initially looked to Unity, then Admob, and finally mediation of the two. Funnily enough at one point I looked at mediation via ironsource along the way as I had heard their Unity integration was pretty good.
If your curious as to the exact monetization mechanisms you can check them via my game below.
I don't know if they _rely_ on it, but recent NBA 2K games apparently have interstitial ads, even though it's a full-price 60USD game with yearly releases already.
Absolutely disgusting, I already doubt the value of yearly releases, as you basically pay for an updated roster, but this is just overreach.
On mobile, the best model seems to be FTP with ads, then a small amount ($5) to permanently remove ads.
I don't develop games, but if I did, this would be a great addition, if I could 1-click this workflow to drive revenue.
This could also have quite the network effect on the ad network itself. You're now able to say 'All Unity apps ship with this network' yada yada.
The dark pattern will be "All games now ship with ads, and developers don't benefit from the ads" type stuff in order to drive premium subscriptions from developers. That or instead of the developer getting the 70% cut of the $5 'remove ads' purchase, they're instead going to get 40% and Unity gets the other 30%. I'm sure they'll figure out how to enforce monetization.
I, for one, hate ads. I will do anything to avoid using ads, but I also need to put food on the table at some point.