It might be good for supply (publishers) short term, but it's worse for demand (advertisers) and for ads quality since it removes personalization opportunities.

It might be good for supply (publishers) short term, but it's worse for demand (advertisers) and for ads quality since it removes personalization opportunities. An open-market like RTB where offer meets demand is more efficient (except for privacy-minded users which aren't even part of the transaction). It's also worse for supply long-term as it ties them more to Google and FB, or to a non-scalable contract negotiation process mad-men style with a handful of advertisers.