Nobody would deny that there exist both amazing programmers and really crapper programmers. The thing is, without any hard data this information is pretty useless. How is productivity distributed among developers? Is 1/10 of developers 10x productive compared to the average, or is it one out of a million? Is is a bell curve or a power law distribution? We don't know. So we cant use the information in hiring, compensation, team composition, project management or anywhere else.