I think all the complaints stacking up into a vendor's own sub-forum function pretty well as a big red flag... probably more obvious than hiding it in a different sub-forum.
For the same reason I don't see much of a point in 'closing these sub-forums down'; it'd close off a pretty visible avenue for customers to signal their problems and warn off others.
I'm going to disagree. Until recently, nobody had much to say in terms of negative feedback and this sort of negative feedback only starts to show up for catastrophic ****-ups on the vendor/maker's end.
I've dealt with vendors here that while they actually provide a service for the money you give them, they are awful at communication, willfully ignore you for months on end, charge different forum members different pricing per mm (for same style of knife), etc. These kinds of things NEVER show up on sub-forums because it's extremely uncommon and confrontational for a member on this site to open X maker's sub-forum and say: "I loved the knife but later I found out X charged me $.50 more a mm than another person who ordered a knife at the same time. X asked for all my money up front and didn't deliver the knife for 13 months; all the while being terrible at communication."
Vendors like I described above are highly lauded and have plenty of forum fan boys who would step in and say, "Hey, man. This knife thing is a hobby for X, so issues are bound to come up," or "He's had family issues!" I'm commissioning a knife for hundreds of dollars, not a wax candle. And who hasn't had family issues?
Despite the legal implications (of which I think Matus is greatly overestimating, but please, somebody, correct me if I'm wrong), the fact that inactive and some untrustworthy people continue to be "Site Vendors" implies that KKF is giving some sort of sponsorship, approval, or stamp of approval. If I didn't know better from interacting with some excellent vendors/makers on this site, I'd assume the status as a KKF approved vendor means jack $hit. I would also go so far to imagine responsible vendors don't like being associated with the irresponsible because it makes them look bad.
Finally, while Tanner makes a good point about keeping the sub-forums up so people can (hopefully) tie up loose ends with a different vendor, how long does this need to last? If you've got the email of the vendor, they can ignore you on email instead of this forum
Is it laziness that keeps them up? Del said good-bye in November and his sub-forum is still up. The site vendor subs are 3 months and 1 year. Did Del say good-bye months before his vendor sub ended or has nobody taken that down?