...With the logic that it's performant, and it worked for Ken Thompson, not realizing that Unix is an order of magnitude less complex than the systems they're building, yes.
Don't get me wrong, as a language I will defend C to the very end (C++ and Java, not so much), but it has a specific usecase: Low-level code, or code where you absolutely need the performance. If you're not in either area, stop. You shouldn't be using C. And, of course, Rust has been eating some of C's lunch of late...
I did a lot of C in the 90s. Appropriately, in the first half to do "systems" type programming (we made development tools to emulate IBM mini computer facilities on PCs and unix , etc), less appropriately in the second half (bulk document formatting for one of the biggest print and mail houses)
One good thing about Unix is, the creators intended for things to be stitched together as insulated building blocks, NOT to be built as monolithic C programs (at least as far as I can tell). OK, I'm really off on a tangent now. Have a nice day :-)
Save the kernel, which is pretty small, yes. Essentially, they realized C wasn't up to the task of writing monoliths, and so they didn't, to keep global complexity low. Richard Gabriel argued that this was part of C's success over Lisp in "Lisp: The Good News, The Bad News, And How To Win Big," informally known as the Worse is Better paper.
Don't get me wrong, as a language I will defend C to the very end (C++ and Java, not so much), but it has a specific usecase: Low-level code, or code where you absolutely need the performance. If you're not in either area, stop. You shouldn't be using C. And, of course, Rust has been eating some of C's lunch of late...