I think I would have to agree that, on a social scale, alcohol causes as many problems as cannabis.  In the cases where people use both drugs equally, or to excess, the damage done to lives and the community is greatly increased.

 In dry (alcohol free) communities, there are always grog runners and there are always those willing to traffic cannabis as well.  Despite the best of intentions to keep communities free from the violence and anti-social behaviour associated with alcohol and cannabis, the problem still persists.