Surely you understand that your argument is disingenuous, right? Nobody wants to start over a new OS or a browser in another language due to the huge costs that no corporation nowadays is willing to shoulder (due to their own interests). Otherwise a lot of people would very definitely write OS-es and browsers in Rust, D, V even, Zig, Nim and a good amount of others.

C/C++ were there first, that's all there is to it, it's that simple.