If they can't afford to keep a forum running that's linked to a shop, maybe they need to take a hard look at themselves? There are people on here that give their time and knowledge for free. They might provide somewhere for people to post, but they don't provide the wealth of knowledge that is posted. That is given freely. They're monetising that. Or are they going to start paying out ad revenue to the most helpful and prolific posters?
Who's forcing these people to share their knowledge? It's not a job, is it? They do it because they're decent people, not because they expect anything in return. Christ it's an ad. You know, the billions and billions of things you see on pretty much every single other website on the entire internet yet here you're whinging over a few pixels on a forum you get to use for free.
I suspect this is the result of them "taking a hard look at themselves" and rather than make cuts to the services / make staff redundant / shut down the forum, they're putting an ad on the site. Crack on I say.
Have you considered learning a bit about how businesses operate before commenting in such a dim manner?