As I've already stated, I can see how exploitation can lead to a loss of profit and how that could be a cause for concern. However, profitability should and could never be the only concern of a game developer, it should be the inevitable outcome of a well developed and popular game. To put this into perspective. CoC makes a profit off of people's impatience for waiting. They could exploit this very human weakness by making it extremely difficult to get resources and/or gems without spending cash. But they shouldn't and they don't, as there is a correlation between how much we enjoy a "good" game and how much we feel is reasonable to spend on it. It's a careful balance that needs to be maintained. I don't mean to belabour this point as it's not something I feel is absolutely necessary for me to enjoy this game. But again I think there are many viable options for implementing this trading system if they are willing to put the effort into mitigating some of the dangers of exploitation.
Which by the look of things, currently they aren't.

