Because "brand new" doesn't mean devoid of context. Within your domain, there will still be common libraries, interfaces, and tools.

C++ is very flexible, with a lot of very mature tooling and incredibly broad platform support. If you're writing some web server to run on the hardware of your choosing, then sure, that doesn't matter. But if you're writing something deeply integrated with platform/OS interfaces, or graphics, or needs to support some less common platforms, then C++ is often your only practical option for combining expressiveness and performance.

Maybe, maybe not. But either way it's just plain rude to charge into a C++ thread to drop a comment saying how the language sucks and you should use (insert other language) instead.

Rust becomes a significant burden if you need a GUI or hardware-accelerated graphics.

Yes. If you're targeting Apple platforms and want to allow clients to use your product in Xcode (the common case) or even need Swift/ObjC interop yourself, using rust or anything not explicitly supported by Apple and Xcode is just too fiddly.

(Shrug) If I want Rust, I'll feed my C++ to an LLM and tell it to port it to Rust. Since we've been assured that Rust magically fixes everything that's wrong, bad, or unsafe about C++, this seems like a sound approach.