The number 0 is interesting in the sense that it is actually a comparatively late and abstract invention. The natural numbers are also mathematically defined as

The number 0 is interesting in the sense that it is actually a comparatively late and abstract invention. The natural numbers are also mathematically defined as either including or excluding 0 depending on the author. That said the issue is really in-band signaling. “I already have this data type which I don’t fully use, let’s use one of the unused values to represent something completely unrelated..”