All of those things have been proven harmful countless times. The small amount of entertainment or relief of stress is not worth sacrificing your health, life and happiness. They should be banned in order to protect the lives of everyone.
In some cases it eases your pain, such as local anesthesia or a dental operation. It would be difficult to make these operations without anesthetics. Stimulants are used for the treatment Post-traumatic stress disorder, which is a very real thing, all of us experience it at least once a life.