You clearly didn't read the article, which repeatedly states that GCD is not just a thread pool with a nice API. The whole point of it is that GCD is a lot mor

You clearly didn't read the article, which repeatedly states that GCD is not just a thread pool with a nice API. The whole point of it is that GCD is a lot more efficient than that because it is optimized across the whole system. The author intentionally chooses to omit this because he is trying to present a simplified example for educational purposes.