In my experience, the sense of "enlightenment" that came from experiments with psychedelic drugs arise from the realization that a very small quantity of chemicals (a dose of LSD is measured in millionths of a gram) can have such a profound effect on your perception of reality and sense of self-awareness.

That said, psychedelic drugs do not inherently bring the user to any kind of spiritual discovery or intellectual awakening. The path to enlightenment requires one to make the conscious choice to continue down it on a daily basis and the self-discipline to not get stuck in the murk and mire.

Drugs are just one of many tools available to facilitate meditations on the nature of being.

Unsurprisingly, however, hallucinogenic drugs are likely more often used as a distraction from reality. This is certainly a valid use-case for many people, but it does not have anything to do with enlightenment.