That quote is definitely not original, and I believe was originally applied to TV (i.e., TV as a medium, singular form of media). (See the origins here: https://quoteinvestigator.com/2019/07/24/tv/)

I mean, not knocking who told you that at all, I think it's funny that they applied it to Medium the website. Just a little tidbit of info about the quote's origins, in case you weren't aware!