It's a pity that's the first result, because it's flat wrong. This article actually talks about the origin of the claim:

https://www.ybrikman.com/writing/2013/09/29/the-10x-develope...

I believe in 10x programmers, because I have known many programmers over the years, and I can think of many pairs where one was clearly 10x as productive as the other. And I think the reason there are 10x programmers is that our profession tolerates a lot of embarrassingly incompetent people. If someone were 10x as productive as an average developer, that would be truly extraordinary. But I don't see 10x programmers as all that extraordinary, because there are so many people who get paid to program but suck at it so bad, that being 10x as productive as they are is not all that impressive.