I think you are being nitpicky here.

When most people say "I write in C", they don't mean abstract ISO C standard, with the possibility of CHAR_BIT=9. They mean "C for my machine" - so C with compiler extensions, assumptions about memory model, and yes, occasional inline assembly.

That is not an argument. ANSI/ISO C standardizes hardware-independent parts of the language but at some point you have to meet the hardware. The concept of a "implementation platform" (i.e. cpu arch + OS + ABI) is well known for all language runtimes.

All apps using the above-mentioned are written in standard ANSI/ISO C. The implementation themselves are "system level" code and hence have Language/HW/OS specific extensions which is standard practice when interfacing with low-level code.

> any language compiled language also has available

In theory yes, but in practice never to the ease nor flexibility with which you can use C for the job. This is what people mean when they say "C is close to the metal" or "C is a high-level assembly language".