You are right that quality of programmer skill and productivity has high variance, but the way people talked about the "10x programmer" was a vague vision that people pasted their ideas and personal bugaboos onto. So people got into increasingly-heated arguments and talked past each other. When we create social concepts, we need to strive for something like falsifiability -- something that lets you look at an example and say "Well actually no, thats not 'high-performing programmer' behavior -- for {{describable reason}}"

Categories matter. We should shape our categories for human happiness and human effectiveness, but categories matter.