I think the real challenge to any admin/promotion/webmaster forums is the results. Admins who come there to get help for their forums/websites often wish for fast results to get their place popular (which is close to impossible), and when they see no result they leave/drop the idea to continue the service. And also because there is a limit to how far such forums can help to advertise other forums (I mean, brainstorming a new form of service seems super hard). No wonder not many survive.
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