The same point could be made about your statement of nearly every one being a failure...
I've joined a party where there was 1 person left on the final boss, and then others joined, and the duty was completed successfully.Almost every time I join one, the party doesn't even fill back up before it becomes apparent there will not be enough time to finish.
My only point with this is that no one person's experience with the game can be used to gauge how the experience must be for a minority, majority, or everyone playing the same game.