You're describing early Unix, with C as the one language to do everything. Some concepts like CI/CD and infrastructure as code didn't exist back in the late '70

You're describing early Unix, with C as the one language to do everything. Some concepts like CI/CD and infrastructure as code didn't exist back in the late '70s and early '80s, but Unix and the Programmer's Work Bench constituted an ecosystem and it was almost all written in C, to support more C code. The modern descendants of Unix have more variety in their tooling, but the languages available still mostly sit on top of C libraries, with compilers and interpreter and runtimes written in C. The serious contenders to replace C -- C++, Rust, etc. -- are more improved flavors of C than radically different languages.