"When publishers choose to use our advertising services, they keep the majority of revenue and every year we pay out billions of dollars directly to the publishing partners in our ad network," a Google spokesperson said.
In other words, "our ads help other entities make money." Well yes, they're ads! That seems, even for a spokesperson, to be a rather stunning evasion. One could even amend the argument as "even if we don't play fair, the folks we cheat still make money."
The problem isn't that the ads are ineffective. The issue is that Google's scale all-but-requires that one advertise with them, and then in turn, they harvest prodigious quantities of data about everything and everyone to target those ads... and demand everyone else play by rules favorable to Google.