I *don't* fully agree with this, just because ANSI C is partly in the business of ensuring that ancient programs still behave to some extent, and ancient programs often use buffered I/O in situations where it isn't ideal but was typically better than unbuffered on ancient PDP11s, or vice versa. :) (And often don't use line buffering, as --- if the program is old enough --- it may predate it.)

That said, on many platforms pipes kinda give you a taste of that environment; as IPC goes, they're fairly slow, so buffered I/O is often a visibly faster option. (Which is why there are lighter but more complex or less documented / characterized IPC mechanisms around on various Unix-like systems.) And I do mean "visibly"; it's still, even on modern hardware, not *that* difficult to end up with programs where you can see visible pauses between emitted characters if you disable buffering completely, whereas even with line buffering the program both loses the pauses and takes less time to run.

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