Actually, C, FORTRAN and C++ are friendly to memory bandwidth, written correctly.

C++ is better than FORTRAN, because while it's being still developed and quite fast doing other things that core FORTRAN is good at is hard. At the end of the day, it computes and works well with MPI. That's mostly all.

C++ is better than C, because it can accommodate C code inside and has much more convenience functions and libraries around and modern C++ can be written more concisely than C, with minimal or no added overhead.

Also, all three languages are studied so well that advanced programmers can look a piece of code and say that "I can fix that into the cache, that'll work, that's fine".

"More modern" programming languages really solve no urgent problems in HPC space and current code works quite well there.

Reported from another HPC datacenter somewhere in the universe.

I'd say it's being able to structure your data however suits your problem and your hardware, then being able to look at a profile and being able to map read/writes back to source. Both C and C++ excel at this.

The advantage of C++ over C is that, with care, you can write zero-cost abstractions over whatever mess your data ends up as, and make the API still look intuitive. C isn't as good here.

Parent talks about new languages, as per the article Fortran or C doing fine. I speculate the benefit of C++ over Rust how it let programmers instruct the compiler of warranty that goes beyong the initial semantic of the language. See __restrict, __builtin_prefetch and __builtin_assume_aligned. The programming language is a space for conversations between compiler builders and hardware designers.