You're right; actually they've been used since the 1920's, and they're still used today (at least where film itself is still used.) Of course, where I work has nothing to do with film, and this guy is young enough to have never seen anything but digital media so I don't blame him too much.
On my last job I worked with a charming young Thai-American woman who was easily half the age of almost anyone else in my department; she'd never seen anything but digital or online either and wondered what I and some of the other old timers were talking about remembering things like 8-track tape. So just for laughs, I made up and gave her an "obsolete media box" containing a VHS tape, a Norelco cassette, an 8-track (bought at Goodwill, even I don't use those any more,) a 45rpm vinyl record, and a scrap piece of 16mm film. She got a huge kick out of it, and maybe learned a little about relatively recent history too.
(Another time, she'd been talking with an older lady in my row of cubicles while I went out for coffee, and when I returned she asked "Jeff...
Who's Jack Benny?"
Did I feel like a fossil! Anyway, I loaned her some DVDS of him and other comedians and cartoons. She didn't much care for Jack after all, but just loved Red Skelton, Laurel & Hardy, Benny Hill (surprisingly) and Chilly Willy cartoons!)