At a smaller company, it becomes much more evident that the contributions are being made more for self-promotion than for anyone's benefit. Either because you know the person making them and their personality, because the volume:quality is out of alignment, or because the person posting the question/answer wasn't actually having the problem and were just posting it for points.
Also the volume of organic questions is on the lower side, and could get easily drown out by what amounts to astroturfing. So in my experience, it never really gained adoption, and withered shortly after it's introduction.