Methadone is still used I think, and it's usually sold on to get street heroin. Over the last few years trials have started that allow GP's to prescribe pure heroin that is gradually reduced in quantity over two years to wean an addict off. So, safe prescription and use, no attendant criminal activity and a program of reduction in use. What are the down sides? Initially addicts are still addicts and will not want to come off it but they are still safe and not causing anyone harm with criminal activity such as theft, shoplifting etc. If they stay this way where is the harm to society? But most after a while will seek to come off the drug in a medically controlled way.
At the moment this does not happen because GP's are not allowed to prescribe heroin, as legally they will be charged with supplying a Class A controlled substance.

"Deaths in the Bible. God - 2,270,365
not including the victims of Noah's flood, Sodom and Gomorrah, or the
many plagues, famines, fiery serpents, etc because no specific numbers
were given. Satan - 10."