I think the point is not that people have to use these services (this is obvious, I think), but instead that these services have no essential economic incentive

I think the point is not that people have to use these services (this is obvious, I think), but instead that these services have no essential economic incentive to not walk back benefits that subscribers were previously paying for. (This is true in all kind of market segments, but it’s especially perverse in online services: bandwidth and storage get cheaper each year, so why are we walking the hedonic treadmill on paying not to be advertised to?)