I do believe a united community action against these exchanges will help a lot

If the community identifies a scam exchange, what we can do here is to warn other users about them, that is why if you check the feedback on the profile of Changenow's rep in the forum, you'll see the numerous negative feedbacks, that is how this community helps. It is the victims that can actually take action by pressing the scam service for their money, taking legal actions or even a class-action lawsuit.