Anything that causes a connection or association of ideas that wouldn't have otherwise been formed holds the potential to facilitate a deeper understanding of ones' self or the universe.
Even in my limited experimentation with drugs, I feel as though I've experienced thought outside the realm of regularity.
I think the psychedelic experience at most produces an unwarranted sense of the profound. You may feel like revelations have occurred, but really they were nothing. Like those dreams when you figure it all out but when you wake up it's gone, or it was something about wearing your trousers backwards to solve the problem of disharmony in the middle east.
That's not to say I don't think there are a whole load of positives in there, but deeper understanding of the universe and yourself? Meh, I say, meh.