There is an option to not link to it for instances like OS writing and embedded. Writing everything in pure Rust without libc is entirely possible, even if an effort in losing sanity when you're reimplementing every syscall you need from scratch.

But even then, your code is calling out to kernel functions which are probably written in C or assembly, and therefore "dangerous."

Rust code safety is overhyped frequently, but reducing an attack surface is still an improvement over not doing so.