On the downside, when it does get updated, compilers take ages to implement the new features, and in the meantime make up busywork like "let's break OS kernels or crypto code to get faster in some random benchmark nobody cares about!"

Don't need C updates for that, a GCC upgrade is quite sufficient! :(

gcc is generally used as a testing ground for new C/C++ features. So in most cases, the compiler supports new features before they are 'officially released' into the language.

It's the complete opposite of waiting for a feature to appear in the compiler.

GCC didn't get sort-of-complete C11 features until 4.9 (2014) and still omits (largely useless) optional features.