There are many well known problems with C++, not least of which are the long compile times, exception handling, and dependency handling. Anyone who has worked with a sufficiently large C++ code base has run into these issues.
The overwhelmingly negative comments here on HN remind me of the pushback that Rust Linux kernel modules received on HN when they were first announced around 2015/2016. Now they’re seen a much loved feature (I understand they solve different problems so the analogy isn’t perfect). I’m not confident that Carbon can be used to solve the issues that arise in large C++ projects as I’ve never tried it but that’s very different from pretending C++ is some kind of perfect language that doesn’t have these flaws and doesn’t need fixing.