I've worked in the industry for almost 30 years, and I've worked with a lot of people in that time. Those that you might qualify as '10x', all have had both of the qualities I mention.
I would not expect any of those people to switch languages and fields and still be a '10x' developer.
Look at someone like Yehuda Katz. Substantial contributions in ruby (merb, bundler), JS (jQuery core team, created Ember.js), and rust (created cargo).
But trying to elevate him or make him uncomfortable (he’s also a really humble dude), but just saying there are examples of polyglots that make substantial contributions.
And yet… we do recognize that some people are impressively better than others at playing piano, running yards, fighting, and all sorts of other narrowly specific tasks.
It’s just that the more creative the task, the harder it to measure how much better someone is.
"Why is DJ Bernstein so great? I too can churn out CRUD apps very fast in ruby rails" - some webshit says this every day on HN.