The intrinsics aren't portable across architectures, so using them vs inline asm (or linking with a .s/.asm file) is more about convenience/ease of use than portability (although they might be slightly more portable across different OSes for the _same_ architecture, e.g. macOS/linux for aarch64).

In some ways, I prefer the "go big or go home" of asm either inline, or in a .s/.asm file, although both inline and .s/.asm have portability issues (e.g. inline asm syntax across C/C++ compilers or the flavor of the .s/.asm files depending on your assembler).