What kids today will never know is that until the 80s and 90s, there was so little content on TV that a show could be popular for decades. I know that cable does reruns too, but it's not the same when you've got 3-5 channels to choose from. Basically every show was as big as "Seinfeld" and "Friends" by virtue of just being the only thing decent on right now. You could reference ancient shows from the literal dawn of recording TV broadcasts like "I Love Lucy" and "The Andy Griffith Show" and reasonably expect a random stranger to know what you were talking about. In a HS art class, all the students marveled at the Japanese girl who'd never seen "The Wizard of OZ". A movie that was annual broadcast event on network TV like the Oscars.
Anyway gag from the holiday episode in an obscure TV sitcom in the 70s is going to be familiar to just about everybody born between 1945 and 1980.