why asm don't support outs instruction
"OUTS" instruction is stated in Intel manual, but NASM doesn't support the 'LODS', 'MOVS', 'STOS', 'SCAS', 'CMPS', 'INS', or 'OUTS' instructions, but only supports the forms such as 'LODSB', 'MOVSW', and 'SCASD' which explicitly specify the size of the components of the strings being manipulated.
https://www.conradk.com/codebase/2017/06/06/x86-64-assembly-from-scratch/
I need to know the reason