Not surprising and not a "wart". C and C++ have diverged since the mid-90s and are two very different languages now. E.g. trying to build C code with a C++ compiler really doesn't make much sense anymore (since about 20 years).
Other than that... I'm not sure what hobbling you have in mind. Many C23 features come directly from earlier C++ standards (auto, attribute syntax, nullptr, binary literals, true/false keywords). VLAs? Though these are optional in newer C standards, too.
[0]: https://en.cppreference.com/w/cpp/language/aggregate_initial...
Unfortunately C++20 designated init has been butchered so much compared to the C99 that it is pretty much useless in practice except for the most trivial structs (for instance designators must appear in order of declaration, array item init is completely missing, designator chaining doesn't work ... and those are only the most important things).