I have lived my whole professional life with this being 'beyond obvious'... It's hard to imagine a generation where it's not. But then again, I did work with EBCDIC for awhile and we were reading and translating ASCII log tapes (ITT/Alcatel 1210 switch, phone calls, memory dumps).

I once got drunk with my elderly unix supernerd friend and he was talking about TTYs and how his passwords contained embedded ^S and ^Q characters and he traced the login process to make they were not just stalling the tty but were actually used to construct the hash. No one else at the bar got the drift.