If you want to show me an ad on your site, then, fine, show me an ad on your site. But I'm not going somewhere else to fetch it.
I think it is an irrevelant technical difference if the ad is coming from a google server or from a - maybe google - server leased by the web page creator. Anyway, now that the percentage of ad blocking users exploded I am sure that within one year a few web hosts start to proxy ads. I am afraid you will be the only one who will be happy with this solution.