Does the existence of I/O operations always indicate there are some side effects?

Moreover, can there be any kinds of side-effectful I/O operations besides "calling a library I/O function" in the sense of [intro.execution]p7 (whatever "a library I/O" means)?

Are they consistent with the clause "[input.output]"?

(I strongly feel there have been something gone wrong for a long time. I have drafted a CWG issue and sent it to month ago, but there was no reply. This time I try to follow the full directives in, except for the link std-discussion in that page which seems to be wrong.)