There are multiple reasons why players would like to complete the Ardougne Diary. Perhaps the main reason is to receive a 10% chance for successful pickpockets throughout Gielinor. This will tremendously help when training Thieving because you’ll get much more experience per hour. Also, completing the diary will let you change teleport locations for convenience. So if you see yourself going to Yanille a lot, then you can change the Watchtower teleport to the center of Yanille. Furthermore, with the cloak, you’ll get unlimited teleports to the farming patch, which will improve Farming run times tremendously.