That's a bit of a strawman. My full comment is that being familiar with your language of choice, and having a deep understanding of a problem means that can produce a solution faster than someone that doesn't. I used the phrase 'churn out', I could have simply said 'produce'.
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.
I would. Languages aren’t as important as you would think. Certain people can pick up the new idioms quickly and run with it.
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.
But isn’t what you said a bit of a straw man too? Back in the music comparison, no one would expect an excellent guitarist to take up playing piano and still be a virtuoso.
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.