1 Eleven: What happens if nobody manages to find the secret door because of the random chance of finding it when searching?
2 Dustin: Then we can’t progress in the adventure any further.
3 Eleven: That seems like poor adventure design. Don’t you want the players to be able to succeed and defeat the dungeon?
4 Dustin: Hahaha!! Oh gosh, why would you want that?

In the "good old days" of roleplaying games, adventures were often treated adversarially, with the Game Master (or Dungeon Master, as it almost always was) trying to confound and defeat the players. Adventures were written in a much more challenging way, with a much greater likelihood of failure than the way modern adventures tend to be constructed.

This often manifested in adventure points where the PCs had to succeed at some task to continue, and if they failed then there would be no way forward. Modern adventure design recognises this as a problem for player enjoyment and seeks to eliminate such barriers.