And both are still not mutually exclusive. Just like how in C or C++ projects you can both use a proper build system, and still have Makefile(s) around (as fallback, or used as simple runners, or also for tooling reasons). Putting vendoring aside, using and not using cargo is itself not an either or. Some projects that incorporate Rust as a non-primary language can still use their own build system, and yet still optionally have cargo around for tooling reasons (e.g. to make LSP just work without much hassle), both at the same time. See this demo for an example (meson for actual building, cargo for tooling/development). I also have no idea why you exchanged this long with a person who clearly lacks basic knowledge. But maybe I grew more abrasive and less patient than the average person with my greying hair.