The entire point of a character line length limit is so that a diff doesn't have wrapping lines on a terminal. And so that most changes become line insertions or deletions rather than modifications of lines.
<i>It probably all started with typewriters (and teleprinters).</i><p>Nope, it started with <i>books</i> where 500 years of typographic practice has taught us that anything above 80 characters a line quickly becomes unreadable.