I think that those people become writers or screenwriters who have some life experience when they have such internal feelings and worries or different life-situation which made the great emotional impact on this person. It becomes the reason for implementation of these remembrances in the story of the book or film, because of the desire of sharing with own emotions.
In my opinion every masterpiece of the world literature or the world cinema has its own reasons and circumstances for creating and promulgation. All writers heap up in their souls besides all pleasant remembrances and feelings also suffering and pain. And there comes a certain moment in their life, when they want to share their own pain with all the world in order to ease it.
The great number of writers created their masterpieces with the realistic basis taken from their childhood. In this manner they express their pain which is connected with bad recollections, which prevent them from livelihood.
The film «Saving Mr Banks» is the bright example of all that was said above. The main character Pamela Travers, with the initiative of Walt Disney, gives the second life to her biographical book Mary Poppins creating the film with her team. It is a great task for her again to outlive and to feel the painful worries, to experience her childhood again that brings the powerful. As the result, the demonstration of the film based on the book of Pamela Travers brings to her the powerful personal significance.
So, due to the book or film writers can get rid of their pain or relieve it and finally remove the burden from the soul.