They provide curation to the ad buyers. Basically the marketplace is broken for both sides.

Could you elaborate please ? You got me intrested but I can't make anything of what you mean by "curation".

If you only want your ads next to quality content or on sites that are not drowning in ads so your ad is more impactful, then Google won’t help. But a third party can provide that through their curated list of sites.

Basically they are in the business of providing human curated targeting parameters instead of the algorithm based that Google supplies.

Thanks :)

Why couldnt they be “sudsidized” by G to uphold monopoly? If they bring in clients that otherwise are not going there? they simply cost more