The key question has to be whether the primary benefit of cross site profiling is to the advertiser or the ad broker. I have a strong suspicion (based on extensive observation) that the advertiser is frequently quite disengaged from the actual serving of their ads - they buy a service "fire and forget" and pay the invoices as they arrive. The broker, on the other hand, obtains a huge demographic database it can use as bait to attract new advertisers. So the primary benefit is to the broker, and both the individual profiled and the advertiser become merely grist to its mill.
Not by chance are these ad broker behemoths the valuable companies on the planet. But because nobody dare stop advertising in the cutthroat world of commerce, the risk is too great to try alternatives to the snake oil. That is indeed the epitome of irony.