I think another factor is the paradox that the user who has enough money to be willing to pay to not see another ad is exactly the most valuable user to advertisers— they've pre-qualified themselves on multiple axes.
So there is always going to be an enormous moral hazard here with the ad-driven-freemium model— always a temptation to run an occasional high-value ad to the paying users, or to disguise the ad as a "recommendation" or position it instead as a "sponsorship", or whatever else. Other than users reacting swiftly and decisively against this kind of thing, it's hard to know how else to keep companies away from it.
I think another factor is the paradox that the user who has enough money to be willing to pay to not see another ad is exactly the most valuable user to advertisers— they've pre-qualified themselves on multiple axes.
So there is always going to be an enormous moral hazard here with the ad-driven-freemium model— always a temptation to run an occasional high-value ad to the paying users, or to disguise the ad as a "recommendation" or position it instead as a "sponsorship", or whatever else. Other than users reacting swiftly and decisively against this kind of thing, it's hard to know how else to keep companies away from it.