Nope. Just because it says so in a book doesn't make it true. When you make a statement of the form "X does not exist", a single counter-example is sufficient to prove you wrong. Lucky for me, many such counter-examples exist, and many have even been discussed in this thread. I'll add one to the list: tourist (Gennady Korotkevich). He's a competitive coder that's several orders of magnitude (e.g. 1000x) better at coding competitions than the average competitor. And the average competitor is a few orders of magnitude better than the average professional programmer who doesn't have algorithm experience. All of this is measurable (at most we can quibble about whether the skill differences are 100x or 10000x or infinite). If you don't believe me, please go and take a simulated Codeforces competition right now and see how long it will take you to solve some set of problems that tourist solved in under 2 hours (or if you will be able to solve them at all - I certainly won't be able to solve the hardest Codeforces div1 problems no matter how much time I put in).

I have a feeling this mountain of empirical evidence was insufficient to change your mind about this. I would appreciate if you could take the time to explain why? Why is this evidence not enough?