I would say that the main reason why people write letters (which I do not know anyone who sends letters anymore) is to inform someone of their current status such as holiday cards to graduation pictures. Other than that, PEOPLE WRITE LETTERS AS AN EASY ALERTERNATIVE FOR COMMUNICATION. Authors write journals because it is a therapeutic alternative to write about how they feel. Sometimes, they just like to write about their lives, or just general information. Same goes for diaries.
Step-by-step explanation:
sorry this answer is late