I don’t agree with that chemical/psychological distinction. Weed and other drugs mess with your neurotransmitters/receptors which are fundamental to our psychological functioning, you can’t draw a line and say this is chemical addiction that causes you to vomit, sweat, and shake, and this is some higher level ”I want it cause it makes me feel nice” addiction. It’s the same thing, just not as severe. And heavy chronic weed use absolutely will cause uncomfortable withdrawal symptoms like headaches, irritability, mood swings, apathy etc.