You seem to be confusing an "executable" with "assembly", probably because they both deal with machine code.

The way how the result of an assembler is bound to needed libraries to create an OS specific executable is irrelevant.

Anything else compiling to machine like C or Pascal needs this step too.

I can even include the same ASM code inside Perl code via Inline::ASM and start it under different OS, as long as it's the same CPU.

> Please re-read what I wrote,

I did.