Languages with unsafe don't just change where the security boundary lies. It shrinks the size of the area that the boundary surrounds.

C++ has artificially limited how much it can improve the memory safety picture because of their quite valid dedication to backwards compatibility. This is a totally valid choice on their part but it does mean that C++ is largely out of the running for the kinds of table stakes memory safety stuff the article talks about.

There are dozens of memory safe languages that already exist: Java, Go, Python, C#, Rust, ... And a whole host of other ones I'm not going to bother listing here.