While this is a very prominent sign, it's actually easy to miss on the way down as you concentrate on your footing and just trying to follow the marked trail.  The most commonly used trail down is the White Cross Trail.  Either route brings you to the Park Headquarters, so it doesn't make much difference if you do miss the turn--in fact it's actually easier to stay on the White Cross Trail, as it's more or less straight ahead of you as you come down from the summit.

But I don't know that you can believe the message that it is the least steep descent!  While there are a couple of very steep, tricky spots on the White Dot Trail that many people would do best to avoid, overall, there aren't many differences between the steepness of the two trails.