IME, there's one big thing that often keeps my programs from being unaffected by byte order: wanting to quickly splat data structures into and out of files, pipes, and sockets, without having to encode or decode each element one-by-one. The only real way to make this endian-independent is to have byte-swapping accessors for everything when it's ultimately produced or consumed, but adding all the code for that is very…
This is functionally identical to the author's example - the file has a defined byte order and you have a choice of doing byte swapping or just explicitly writing out the bytes in the defined order. The author is saying your goal of avoiding "having to encode or decode each element one-by-one" a misguided optimization.