I don't know much about biology, medicine or toxicology so I can't really refute your argument but your first sentence triggers all sorts of red flags for me, mainly because it appears way too simplistic and fails to provide any source or real scientific argument.
What does "washing out" mean and why is it bad if remains of pot can be detected in urine months later? What does the fact that the human body is able to "cope" with alcohol quickly have to do with the relative danger of the substances? I seem to recall that the human body is able to process cyanide pretty quickly to get rid of it for instance, I don't think that's enough to say that it's less dangerous than pot.
I definitely don't think we should push people to smoke more (I'm not a smoker myself, pot or otherwise) and we should definitely fight teenage smoking but your pseudo-scientific babble and anecdotal evidence resembles way too much the type of "argument" I see from anti-vaxxers and similar unscientific movements for me to take it seriously.