Revelations are not always something that people want to shout to the world. Look at how long Sister Lucia and the Church kept the 'secret' of Fatima...
Also, many people who come across such 'sacred' knowledge often want to keep it secret or hidden -- from the profane (or evil folks or the unworthy). Examples that easily come to mind are the Prophecies of Nostradamus (admittedly obscured by Nosty himself), the secrets of the alchemists, Freemasons, and Crowley.
I would think the point (and what probably drew us here in the first place) is the challenge of breaking the code - versus the validity (or worth) of the message encrypted. "Be sure to drink your Ovaltine."