They don't unlock any mystical understanding of the world, because everything that happens while on drugs is still subjective experience.

Is that not an assumption?

Give me a definitive answer to what consciousness is and I'll give your words credence. Until then, your guess is as good as anyone else.

There needn't be anything other than a single subject for there to be an experience of "reality", just give it a mind with an imagination and, all of a sudden, "objects" can spring up. Don't believe me? Look no further than your dreams. Imagined objects in a dream are good enough to pass as real, separate, unconnected objects while dreaming. When we wake up, it becomes obvious that it was all imagined -- the whole world in the dream was our own mind. A whole universe inside of a subject's mind!

In other words, perhaps all you need to understand the nature of the universe (reality) is to understand yourself. Or perhaps not.

It may be an assumption with bodies of evidence to support it, but an assumption nonetheless.