1a) That is sub-optimal for ad publishers. I think in building such a system you have to assume they want to make the most money. And while ANY ad may not make much money, it's certainly not capped at the $0 they can expect from NO ad.
1b) Also: imagine if you implement AdCompanyX's html, and you see nothing. Is it broken? Out of ad inventory? Not yet parsed your page? It's not an impossible problem, but it adds UX complexity.
2) As I said in the original post, It's possible it's actually too far of a leap to go from dinosaurs (to kids?) to games. If this is the case, imagine some sort of fitness function scoring how close the best inventory match is to the content of the page. There's a cutoff under which you show no ad. Dinosaur could likely still be close enough to pass this test. Especially given the relatively little text in this example.
FYI your cutoff idea is what Google actually does. Ad quality is a problem Google works on. The main complaint people have is that Google doesn't do a good enough job of overruling users "for their own good" when those users are consistently actively telling Google what they want to see.
If that were true, why would there be a need for Adblock? Google would just stop showing ads to people who don't like them, or would be showing us all such great stuff that we'd be grateful for them.
