He's not saying that it doesn't exist, he's saying he doesn't believe that's who startups should hire.
He's making the argument that 10x isn't solely about the person and their technical abilities. You could have a "10x developer" who joins a team and performs poorly because they're not motivated by what the company is building, or they have a shitty boss. What makes the person a good performer is the environment they're put in combined with their technical abilities.
He is though, right up in the title. And then he changes the subject to discussing why he prefers hiring inexperienced developers; which is fine, I guess, as long as shitty software is your goal. That being said, the rock-star/code-ninja culture isn't really helping anyone. I once got hired for one of those positions, but failed to realize in time what a shitty pool of wishful thinking I was diving into. From my experience, it's not the magic it's presented as, it's not about solving 10x as many problems in the same time; rather about skipping 10x as many problems and doing exactly what needs to be done, because intuition and pattern matching is much more effective than logic reasoning for heuristics.
