Because we're talking about different things.
A master craftsman will solve a problem quickly, efficiently, and elegantly, combining insightful attention to detail with speed and effectiveness.
A master creator will produce work of lasting relevance and power. The metric is quality and impact, not speed and efficiency.
Occasionally you get people like Mozart who combine elements of both, but they're exceptionally rare. And they work best in a relatively limited context which they have mastered completely. They're not perpetually chasing the latest shiny. (Mozart basically knew one style. Even he would struggle to master all the languages and genres that are common today.)
Turing would likely have made a poor backend developer, but he produced work that had lasting impact.
A typical 10X developer will be more like a master builder than a master computer scientist.
I don't find the labelling offensive, because it's clearly realistic. Some people are just very, very good. They produce clean, tight, code at speed, far more quickly than muddlers who produce reams of mediocre code which creaks along, breaks when you look at it, and doesn't actually solve the problem.
But a 10Xer isn't going to be good at everything. If they mostly do backend, they're not going to go toe to toe with game devs. Etc.