I paid for a ‘featured spotlight’ ad on Gamedev.net. So far I haven’t gotten any apparent boost in traffic. Two people that I know of in the industry have ad-blockers so didn’t even see the ad. I wouldn’t say that adblockers are stealing, but it’s true that pretty much nobody wants to see ads. Taken to its logical conclusion pure advertisement paid content would not be a viable business model. Those sites would have to massively downgrade content, require subscription fees, rely on free user submissions, put ads in a more obtrusive context, and/or a combination of these measures. None of these are good solutions, and I don’t know what a good solution would otherwise be.
Considering that in the best case scenario I stand to make $50,000 from a site-license to a publisher, $500 is a pittance. But that’s only worthwhile if the link that gets me that sale is the ad itself, as opposed to other measures such as a new post.