Ads pay out little but you can make decent money out of a site with traction. We don't even bother with ads on a lot of games at http://www.rocksolidarcade.com. The traffic is more important.
In terms of success? They took VC and grew very well, we bootstrapped our way to 5 employees without taking a dime. Total investment under a thousand dollars and profitable after a few months. In terms of raw game play counts, I'd bet money on us being ahead.
All in all, I'd rather be in their position not mine, but I guarantee you, the strategy outlined is not the reason why. And their greater success does not mean that I should not be allowed to have an opinion on what I've been doing successfully myself for years!
By the way, if one must always learn from more successful companies, it would be hard to argue the case for Zynga to switch their monetization strategy over to ads.
Here's a CNET article from 2007 touting the benefits of ads embedded in flash games, one of which is "Even if the game is stolen, even if it runs on a site surrounded by other HTML ads, the ad can still play in-game": http://news.cnet.com/8301-17939_109-9797689-2.html
I don't think this is especially novel; not for ads but I remember writing code back in the 90s for Java applets to check that they were being served only from the original website.