This is probably the worst advice on Rust project organisation I've ever read. I absolutely loathe opening up a Rust project that adheres to zero defaults and

This is probably the worst advice on Rust project organisation I've ever read. I absolutely loathe opening up a Rust project that adheres to zero defaults and uses makefiles where cargo would completely suffice. Unless you have a mixed codebase cargo will work just fine. Also that multiple Cargo.toml shenanigangs is much better solved with multiple projects and git dependencies, given that a projects of that size will have different teams anyways, and if it doesn't have different teams then you don't need anything but an easy to maintain and debug monolith.