The business has to pay more to acquire customers, which drives up the cost of goods. Indirectly the consumer pays in mobile bandwidth costs, and publishers are forced to show ever-more ad units, refresh every 30 seconds, paginate articles, or add content recommendations, all because AdTech takes 85% of the ad spend that use to flow more directly between publishers and advertisers. Much of that went to the cost of staffing a sales team, but those folks were doing human review on campaigns, so ad quality was high and fraud was low. With unlimited digital ad variations, ad networks have to police a mountain of potential bad ads, which can be directly malicious to the user.
I can spin up 1000 banners and text ads, but only spend a dollar. See the problem? They all still need review. Instead, GOOG relies upon AI and user reports, which they promptly ignore. Meanwhile, they serve up so many mobile redirects that publishers have to pay yet another vendor for protection against the crap Google doesn't vet. As a publisher I'm not really interested in showing my audience ads that automatically redirect them away from my content and to a scam $500 Walmart Gift Card landing page. Yet, if I want to have access to Google demand, I have to take the bad with the good. What choice is there? Exist and use Google, or pass on 60-90% of revenue while competing for the same audience?
As an advertiser I have to count on Google's reporting to tell me if I'm making positive ROI and they are constantly finding new ways to convince me that they made the sale. They bill for ads that were never seen and clicks that went to nowhere. Occasionally you'll see a discount on your bill for "Invalid Clicks" but you'll never see anything auditable about it. If I don't police my site list, I might end up funding websites run by terrorists and/or money launderers. Honestly how many US citizens who are shopping for cars do so on .ru domains? If you're not vigilant, that will be 20%+ of your ad spend. Yet, if not Google or Facebook, where can I reach a relevant, large audience with a small and variable ad spend? Not with DSPs, not with agencies, not with direct ad buys.