This seems hard to evaluate without a quantitative comparison to the abundance of bugs in the package ecosystems of other languages at the same age. So, for ins

This seems hard to evaluate without a quantitative comparison to the abundance of bugs in the package ecosystems of other languages at the same age. So, for instance, how many correctness bugs existed (or, alternatively, had been found and fixed) in the Python ecosystem when Python was ten years old? The author makes a subjective claim, but from the few other languages they mention it seems they are comparing primarily to older and more stable ecosystems.