> In low-level systems software, which is a primary use case for C++
I don't this this is true. There is A LOT of C++ for GUI applications, video games, all kind of utilities, scientific computing and others. In fact, I find that the transition to "modern" alternatives from native GUI toolkits in C/C++ has led to a regression in UI performance in general. Desktop programs performed better 20 years ago when everything was written in Win32, Qt, GTK and others and people did not rely on bloated Web toolkits for desktop development. Even today you can really feel how much more snappy and robust "old school" programs are relative to Electron and whatnot.
To clarify, you think that low-level systems software is only a secondary use case for C++? The part you quoted does not make claims about whether there are other primary use cases, just that low-level systems software is one of them, so it's not clear why it being useful elsewhere is a rebuttal of that.