I hate to get a head of the official answer, but I do know that vbulletin (the software on which this system is built) is very robust and allows the admin a lot of leeway in how the system is crafted. Other sites of which I am a member who use vbulletin to operate their forums do have the ability to subscribe and eliminate certain portions of the advertising. I just thought it might be an option for those of us who don't mind paying to support the board to get rid of the ads. I also understand that the ad revennue is probalby based on either views or clicks. If it is based on page views then obviously the operators don't want to allow people to opt out of the banners being counted everytime a page is refreshed. IF it is based on click throughs, then they aren't getting any revenue from me anyway and anythign that I paid to get rid of it would be money found for the system to operate.
I agree that keeping as much of the site as possible free is a great thing. I too applaude the powers that be for the decisions they have made and the robust community online that they support. I'm not really trying to cause waves, just curious mostly.
TDS