Pm is not unlike sales. It's a function with a strong value but which has metastasized because of compensation. Everyone knows the path to CEO and top compensation is ( roadly)through pm. Which means it attracts all sorts of people whose primary quality is that they want to come out on top. They don't make good PM's, they often don't have strong engineering or business backgrounds...and there are a ton of them. The ultimate downfall of the software industry will be from our over reliance on the army of mediocre PM's growing each day....