That's just the compilation toolchain. For better or worse, existing C projects have their whole workflows sitting on top of bespoke tools with the assumption t

That's just the compilation toolchain. For better or worse, existing C projects have their whole workflows sitting on top of bespoke tools with the assumption that there is a C toolchain. And Rust projects assume cargo, etc. You're more or less doing a parallel rewrite in Rust to adopt Rust in an existing C project. The Linux kernel already does extensive bespoke tooling and it's low level enough to skip cargo and such. It's rare to see that approach in Rust projects in the wild.