In early days, many/most people also read their email on terminals (or printers) with 80-column lines, so breaking lines at 72-ish was considered good email etiquette (to allow for later quoting prefix ">" without exceeding 80 characters).
One of the technical marvels of the day were mail and usenet clients that could properly render quoted text from infinite, never ending flame wars!
One of the technical marvels of the day were mail and usenet clients that could properly render quoted text from infinite, never ending flame wars!