If the Koran forbids alcohol and drugs why does it allow tobacco?

I was just wondering why since I see my Muslim neighbors smoking, almost all including the 90 yr old grandmother smoke like a chimney but don't drink or use drugs on religious grounds. I have no problem with it I was just wondering why cigarettes is "clean" and OK with the Imams and Clerics? As a non-Muslim I find cigarettes every much a drug as marijuana or alcohol, and more addictive.