Actually the transition from "offline editing" and "electronic terminals" was not short at all. Teletypes (aka "typewriters which can recieve content encoded in electricity, next to the user keyboard") date back way beyond computers, and were still in use in the 1980s (but evventually superseded by fax). Teletypes were cheaper, faster and more convenient then video terminals. Don't underestimate of having a printout of your session, especially when being online (i.e. connected to the mainframe or mini computer) is something valuable and your terminal is "dumb" and has no storage (except paper).