Most smokers already know the damage that tobacco smoking does to their body, but they cannot stop because they are addicted and see no reason to stop smoking. This is why they feel reluctant of stopping because they feel that if they stop, they will not be able to overcome stress and tension.
Quitting tobacco can be one of the most hardest thing to do, not impossible but highest level if there is a bar to measure even tough compared to quit alcohol and the reason is simple, continuous usage of tobacco brought lot of chemical changes in our brain and without the dopamine that tobacco gives, one will feel restless and highly aggravated.
One who is smoking for year should never attempt the cold turkey method, they should consider the gradual decrease, it could take even a complete year depending on their addiction level.
Just like every other addiction, quitting addiction of any kind is more or less a war(inside and between oneself)...
And a gradual approach as you said, can do that magic...