In what way is The Outsiders a call to action?

The Outsiders ends with its own opening sentence, as Ponyboy begins to write his assignment for English class, and it becomes clear that the story the reader has just finished is the assignment itself. It is inspired by Johnny's letter to Ponyboy, in which he explains what he meant by his last words: "Stay gold." There is no reason for lives to be cut short because of senseless violence between the Greasers and the Socs. Ponyboy feels called to action by Johnny's note, and wants to save the lives of other hoods who might end up like Dally. In Chapter 12, this goal is underlined:

"There should be some help, someone should tell them before it was too late. Someone should tell their side of the story, and maybe people would understand then and wouldn't be so quick to judge a boy by the amount of hair oil he wore."