> the misguided idea among some that as long as a dependency isn't through FFI, it doesn't count as a dependency, is one of the things I dislike the most about Rust culture

I have not heard that idea a single time. There's definitely the idea that FFI dependencies "count more" / add more baggage (because there's a bigger risk that the build fails, it's harder to investigate memory safety, ...). Absolutely not that a non-FFI dependency "does not count".