Hemp is actually a quite useful substance, though I would not smoke it (anymore). Also, the strains cultivated for drug use are not exactly identical to those that were grown for rope, cloth, paper, etc. They have been hybridized to increase the THC levels.
Alcohol is not a man-made drug either. If you watch birds or animals around fruit trees, you will find they do eat old fruit off of the ground, it gets them drunk. Alcohol!
I won't tell anyone NOT to use, but to think that spirituality is based on drug use....nah! There are dangers affiliated with any drug usage, I will no longer "play with fire" regarding them.