This is partly a historical response to the violent suppression of such beliefs by other religions. Our spiritual ancestors had to safeguard their cherished beliefs (not to mention being strongly motivated by a desire to avoid having their privates burned off by crucifix-wielding nutcases).
It’s not like that any more. But it is still wise to approach occult study gradually, step-by-step. If you are going to get the most out of the teachings, new knowledge has to be assimilated carefully, with each step based on previous lessons. This also helps protect eager newcomers from playing with forces they can’t yet control, and causing themselves lasting psychic damage.
But we are not like some occult ‘orders’, who thrive on secrecy. We hide nothing out of guilt, or shame, or some weird desire to tantalise newcomers.