The logic of this argument appears to be that soft drugs should be legalised for consistency's sake. As you point out: "Alcohol ... causes more death and dismay than any other drug available." Surely this is an argument against legalisation.
Our tolerance of alcohol and tobacco has, in many respects, proved to be disastrous. The failure of prohibition reminds us that retraction of legalising a drug is almost impossible. We must be convinced that legalising soft drugs will not be another costly decision for society.
Dr GM BIERMAN