Biggest issue I have with this would be scam or phishing ads being shown and something that we can't moderate as it isn't our own ad network. Google is notoriously known for allowing scam ads on their network as we have seen previously. Even the FBI recommends using an adblocker for this very reason.
With that aside I don't see how this would bring in any new users. The previous blockchain did the exact thing (and subsequently on their own network) pre-Hive and all it did was to offset a small portion of their massive AWS bills.