Isn't the problem that the ad network(s) would have to extract a fairly high price from us to sell such an opt-out? More than they'd estimate they could make from us... I'd bet it would have to be calculated based on what they've got on you already (so in that sense having been using an adblocker might make you less valuable and thus cheaper for you buy your opt-out).
I would pay a third party opt-out enforcement service, but I would not give a single thin dime to actual advertising companies in exchange for an opt-out, nor would I pay a third party service if they're going to pay such advertisers.
But a lot of them have opt-outs already, which are presumably free. I think we're talking about the just the convenience cost of exercising all of them on my behalf.
