I've written that a product manager need not have industry or domain experience to be qualified. Today, a colleague challenged me with a very good, related question: how can a product management consultant come into a company for a few months and understand the market for their products better than executives in the company do after years of successful operations?
The analogy I like to draw is to psychology. (After all, product management is like therapy.) Imagine a couple that has been married for ten years. Who can gain greater and deeper insight into the wife's psychological problems? The husband who has known her for more than ten years, or a good psychologist after a few months of intensive sessions with her?