When you say something, it doesn't make it true.
Actual data on the subject says otherwise. And even common sense points out why this is true. When you make it more difficult for people to get something, it shouldn't be surprising that overall usage goes down a certain amount as for some people, the inconvenience of acquiring that thing outweighs their desire to acquire it.
Nobody thinks it will stop smoking entirely. But it will reduce the amount of people who start smoking.