Manipulating a string can be a complex operation in terms of memory and CPU instruction.
For systems programming you don't want to hide that complexity.
e.g in Rust you `a+b` two strings, it is a trivial rust line but it won't compile down to trivial assembly.
There's a case to be made for languages that closely map the way processors works, like C.
Though C doesn't closely map to the way processors work. It closely maps to the way the PDP11 worked, but for modern processors it's pretty far. It doesn't expose any of the ideas of caching, for example.
I got stuck at some elementary string manipulations.
So I said, forget this. I pulled out Python, and solved it in a few minutes.
This proved to me, that while C has its place, it just does not meet the programmer productivity of other more modern languages.
Nevertheless, we need a modern replacement for C. But honestly, I just don't think Rust is it.