I think this is not completely unrealistic. I do not block every ad, but I do it selectively for sites that irritate me. For instance, Facebook ads get blocked because I don't ever want to see those fucking teeth ads again. Also, I need to filter Facebook to block all of those surveys anyway. Slashdot apparently offers to remove ads for free if you post several good comments, but I have never taken them up on that and clicked the box because the ads here are not that irritating.
I don't think the advertisers will ever come to a consensus that blinking popup ads of dancing babies with awful teeth schilling for fraudulent mortgage companies that install malware are below a certain standard of taste and should not be used, but the sites I use most often already seem to have the self-respect not to run crap like that. Maybe if I spent more of my online time searching for free ringtones, things would be different for me.
Put another way, I am too lazy to block ads unless they piss me off. Maybe the folks at Google are expecting a lot of people to be like me.
Computer programs expand so as to fill the core available.