Like many other sites AllRPG are using an external company who supplies the popups. It's not AllRPG who is running the ads, but the ad supplier. We had the same issues a couple of weeks ago when the rate of suspicious ads increased dramatically. We stopped having any pop-unders, as a result Rendelius, who owns RPGDot has $40 less income from the site than before. As he had to keep on pumping money into RPGDot before that also, he now has $40 more every month to put in. $40 is only a fraction of the total monthly costs.
Running a site with a large visitor count costs money. Ad revenues have dropped to a point that one can ask the question if this is ever going to be profitable. Banning AllRPG will hurt AllRPG much more than the ad provider, not every site is in the position that they can cough up the money every month themselves. As AllRPG is partly responsible, the decent thing to do would be to put your complaints to them. Afterall it's the complaints we got from visitors that made us stop the popunders also.