Calling Rust a "better Java" and not a credible alternative for C++ for "extreme systems software" without further detail is an opinion that I find hard to take

Calling Rust a "better Java" and not a credible alternative for C++ for "extreme systems software" without further detail is an opinion that I find hard to take seriously. So I'd like to understand your viewpoint better. Could you elaborate on what aspects in C++ specifically make it so much better suited for these tasks from performance and maintainability perspective?