And -- as I was responding to a specific point only, but the title of this thread is "Hidden Truths and Secrets in Buddhism", I would balance this out by referring to the "Handful of Leaves" simile used by Gautama Buddha, our teacher.
Once the Blessed One was staying at Kosambi in the Simsapa forest. Then, picking up a few Simsapa leaves with his hand, he asked the monks,
“What do you think, monks: Which are more numerous, the few Simsapa leaves in my hand or those overhead in the Simsapa forest?”
“The leaves in the hand of the Blessed One are few in number, lord. Those overhead in the forest are far more numerous.”
“In the same way, monks, those things that I have known with direct knowledge but have not taught are far more numerous [than what I have taught]. And why haven’t I taught them? Because they are not connected with the goal, do not relate to the rudiments of the holy life, and do not lead to disenchantment, to dispassion, to cessation, to calm, to direct knowledge, to self-awakening, to Unbinding. That is why I have not taught them.
i.e. Everything needed to practice for the goal of Buddhism is well known and publicised, and in my experience, the Buddha was right...