That's true I guess if we're going to stick with the pure definition we should outlaw coffee and tea.
Right now alcohol is legal and there's plenty of proof that it causes huge problems. In my view even though it's illegal I would say pot falls into the same class as booze. The government is not going to go back to the days of prohibition. There are plenty of, "drugs," that fall into this category.
The government should be going after the really bad stuff like heroin or meth, and at the very least ignoring other stuff.