Maybe, but "de-facto" and "actual" are still not the same, and if I write code that relies on them being the same, then I have only myself to blame when my code

Maybe, but "de-facto" and "actual" are still not the same, and if I write code that relies on them being the same, then I have only myself to blame when my code breaks. e.g.; there are C-compilers that usually zero most allocated structures. That's an implementation detail however, not a feature of C. C doesn't guarantee you zeroed memory anywhere, and code that assumes otherwise is just one compilation away from a desaster.