They aren't just paying "with their attention" — but also with having all of their behavior, across the entire web, recorded, tracked, and modeled by folks with

They aren't just paying "with their attention" — but also with having all of their behavior, across the entire web, recorded, tracked, and modeled by folks with demonstrably unclean hands, whose incentives are aligned against them. That is a categorically different bargain than merely having something that competes with the content for their attention. Just because the viewer may be ignorant of it doesn't mean they aren't (implicitly) making it.