Will makes a dubious claim to support a dubious distinction. Plenty of large, complex infrastructure is written in Python.

   > Dynamic programming languages are arguably still far from systems languages,
   > since dynamic types and idioms like “ask forgiveness, not permission” are not
   > conducive for good code quality.

I find it amusing that, when asked to give a defining characteristic of systems programming, key figures behind C++, Rust, D, and Go gave radically different and unrelated answers: "client applications," "resource-constrained applications," "cloud infrastructure," and "unsafe pointer casts."

If anything, a more practical definition is "only C and C++ are systems programming languages, by fiat, because it's an artificial category whose historical roots have long since lost pertinence."