I would argue that marijuana, on a social scale as you put it, is no more a detriment than alcohol.
I agree with the argument made by Bill Maher that the U.S. (and Canada too) are nations of speed freaks in which we are told to pop a pill to be alert, drink caffeine to stay awake, etc. in order to maintain a specific level of output in the economy. Instead of being concerned about the pharmaceutical companies, marijuana is a concern because it does not promote socio-economic productivity. Like I said, the above sentences have been paraphrased from Bill Maher, but I absolutely agree with him.