...remembering that human beings cannot produce 20,000 unique sounds, even if you were to include belching and hawking great globs of phlegm {which I think counts in Chinese}, the linguistic powers that be--whoever they are--threw in tones, possibly to ensure that no foreigner over the ages of thirty would have any chance whatsoever of understanding that Chinese language.
In his humorous take on language, J. Maarten Troost points out that humans are limited in their ability to produce a vast array of unique sounds, humorously noting the inclusion of unusual sounds like belching. This observation leads him to explore the complexity of languages, particularly Chinese, which incorporates tones that make it especially challenging for non-native speakers to learn and comprehend.
Troost suggests that these tonal elements are deliberately complex, possibly as a means to maintain the uniqueness of the language. The implication is that understanding Chinese is extraordinarily difficult for foreigners, especially those beyond a certain age, due to the intricate nature of its sounds and tones, which adds layers of challenge to the learning process.