I think this myth stems from a lack of understanding of what we consider to be "work". For example, one developer could crank out 10x as many features as their peers, but never consider deploying or maintaining. The reality is that they are making everyone else slightly less productive. Similarly, they could work on 1/10th of the features, but help their 10 peers become twice as effective. Taking this even further, there's developers who can complete 1/100th of the features as their peers, but help thousands of other developers become 5% more effective.
In my mind, the mythical 10x programmer is the person that can complete business objectives while helping make those around them more effective. This isn't actually a myth, and "10x" is a completely arbitrary number that doesn't mean anything. It might as well be 2x or 1.1x -- they all mean the same thing to me. They can do their work at 1x speed, a baseline set by the developer in question and not their peers, but they can simultaneously help others around them be more productive.
In my mind, the mythical 10x programmer is the person that can complete business objectives while helping make those around them more effective. This isn't actually a myth, and "10x" is a completely arbitrary number that doesn't mean anything. It might as well be 2x or 1.1x -- they all mean the same thing to me. They can do their work at 1x speed, a baseline set by the developer in question and not their peers, but they can simultaneously help others around them be more productive.