Actually, OP very explicitly said to ignore bugs and was only talking about gameplay. Which is why they talk about extreme replayability being the requirement on old games.
I just realized you were talking about who i responded to, not OP. But still, they weren’t only talking about bugginess.
The basic mechanics of a game (eg. Mario) better be fun, and those first couple of levels better be fun, because that’s what you’ll be doing a lot. It’s similar to how the swinging in Spider-Man better be fun because you’ll be doing it a lot. But the it also has more complex fighting, side content, and a story. You can mess up a lot more while there’s still enough to keep it entertaining.
But people don’t remember the majority of games that were not very good. World Games was just a game that came to mind on the NES as being not very fun, but more importantly forgotten.