I think that already understands the libertarian argument for legalization of marijuana. In her first comment she compared it to alcohol, so she's not arguing that marijuana has no negative effects; she's just arguing that making it illegal is not the solution. That's essentially the libertarian argument as well.
As far as I can tell, no one who has commented disagrees with her. The purpose of my post, as correctly identifies, is to provide information on the effects of marijuana so people can make better informed choices for themselves in the places where it is becoming legal.