It seems the thrust of the comment is that you can't trust the critques of people in the same business. This is not quite correct. You can trust the critiques of others in the same business to be based on their point of view. This doesn't make the critique inherently untrustworthy. It does however, mean that when such criticism is recieved, a listener must attempt to understand that point of view and decide if the viewpoint (or critique) reflects the listener's values. If it does, the listener must judge the critque and decide how to change; if it doesn't, the listener can continue on without sparing a thought for it.