I agree with Marky here, just because someone sold one time or two does not make him an extractor. If they do earn much, that dent in KE will stay for a long time.
Again it's a simple tool, it's easy to understand. It gives you a quick measure of a behavior. Someone with KE = 1 and KE = 1000 are certainly different and that is what I am after. It is not a labeling tool.