Knowing and doing are two different things. Yes, you'd get fewer accidental overdoses from people getting stronger stuff than they thought. But you'd get more (possibly a lot more) people overdosing from chasing a high despite having built a tolerance, or from doing crazy shit while high, and drug psychoses.
> Having drugs being illegal make them stronger, as they have to be transported in secret, and create derivative drugs to fill lower price ranges for long term addicts, such as crack and oxy.
And with full legalization, you'd have billions of advertizing dollars invested into marketing and research departments by companies trying to convince people to get high from their brand.
Remember, I am not arguing for the status quo or against some degree of decriminalization. I am arguing that the larger observed harm caused by alcohol is not useful evidence that illegal drugs are inherently less dangerous than alcohol.