If you buy ad space, the quality of the content does matter. No one buys ad space devoid of content of some sort. Good content does more than attract eyes, but

If you buy ad space, the quality of the content does matter. No one buys ad space devoid of content of some sort. Good content does more than attract eyes, but advertising next to good content elevates the advertised product. People associate it with the quality of the content. So no, Google has ever incentive to provide high-quality content precisely because paying customers are being sold on that as a major part of advertising with Google.