I'm curious how untargetted they are - if I'm searching for python, how untargetted is a python book ad? I'd be more inclined to purchase that rather than a remarketing adroll targetted ad that's just spewing me the same item that I purchased 30 minutes ago
Edit: The problem in sustaining this growth isn't just marketing either. With increased traffic come increased server, maintenance, and engineering costs which may not be possible to support with untargeted ads as advertisers won't pay big money to show ads that have poor conversions.