The classic episodes that everyone is supposed to know and love is a small fraction of the series.
I don't know. Couldn't you say the same of TOS? Or most venerable cult series?
In both cases, you're going to have the knowledgeable fans who can reel off chapter and verse about umpteen episodes. And the more casual viewer who is only going to remember a few classic episodes or moments.
"Let's see, there's the tribbles, and the one with Joan Collins, and that time Spock had to mate with a Vulcan chick or die, and the one where Kirk outsmarted some sort of computer . . . ."