The point is that old mass media ads are pretty much accepted as a bottomless pit with unclear outcome and that there is a whole industry specialising in independent result assessment.
Online ads promise perfect monitoring, but that is not only provided mostly by the advertisement channel provider itself (quite the opposite of independent) but also only useful for ads that aim for immediate reaction ("buy now!"), it does not tell anything about brand awareness effects.
I don't think that you are disagreeing with GP at all.
Bingo. No one rushes to the store to get Downy because of a Facebook ad, but they might start buying something else a few months later if another brand has been consistently hitting them with ads.
Online ads promise perfect monitoring, but that is not only provided mostly by the advertisement channel provider itself (quite the opposite of independent) but also only useful for ads that aim for immediate reaction ("buy now!"), it does not tell anything about brand awareness effects.
I don't think that you are disagreeing with GP at all.