C was a terrible language from day 1. But cheap high-performance compilers were rare until fairly recently, and language ergonomics or expressiveness are hard to measure objectively, whereas "my language is faster on these unrepresentative microbenchmarks" is easy to measure. If unix culture had cared about safety or quality or really anything other than microbenchmarks and the feeling of superiority you get from doing something gratuitously difficult they'd have rewritten everything in OCaml back in the '90s, sure. But kernel developers love the macho culture of being a hardcore elite even more than regular developers, and once you've framed the question "how fast a language should we use?" it's very hard to answer anything other than "the fastest language possible".

Rust is the first decent language that can match C on the silly microbenchmarks. D doesn't, Ada doesn't, and Zig is far less mature than Rust. That's the real reason it's succeeding where previous alternatives failed.