I should clarify that by referring to it as a myth, I'm not denying in my post that there are people who are 10x as productive as most people.
The "myth" is that there was a formal study done and these performers were identified. The reality is that the study was looking at the difference best and worst performers, not best vs average, which is an important clarification.
This has since evolved to a further myth that 10x programmers exist, but are somehow always harmful and should be avoided. There are plenty of articles examining "The 10x programmer myth" which, with no more evidence than the original assertion, put forward that 10x programmers should be avoided.
And here in this article, it gets re-written again, that they aren't even 10x as productive, and just produce ten times as much in terms of LOC but it's all terrible code!