There
is a class of C code that can be made
extremely portable: pure computations. This allows you to write self contained code with zero dependencies, and if you're willing to give up on SIMD you can stick to fully conforming C99.
It's not applicable for everything, but we do have some niches where it comes in handy: cryptographic libraries (I've written one), parsers and encoders of all kind, compilers…
For instance can a mobile on web engineer quickly take TweetNaCl or Monocypher and use it in their stack? Yes. They may need to write some bindings themselves, but if they can run C code at all it's fairly trivial.
