A moderator is supposed to be unbiased and protect the best interests of the forum, while you have traders who are also moderators there is the opportunity for abuse.

Take for example, if someone is making negative comments regarding a trader these threads can go on for a few pages and its important information that the enthusiast community should be aware of however making negative comments regarding a trader who is also a moderator could result in the thread being closed even though it breaks no rules or the thread starter being watched for an opportunity for a revenge ban.

Im not suggesting that this has happened, only that I believe the opportunity for abuse is there simply because the moderator has the ability to look after their own interests as well as the forums rather than remain unbiased and because of this I personally agree with Phil