How would you convey information contain in a journal to the players?
For example, if the players were to come across the journal of a wealthy NPC which, as DM, you want to be relevant to the current quest but also contain hints/clues about other goings on. Such as secret societies or dodgy dealings that aren't necessarily important but could be part of some side quests/whatever.
I don't think it makes sense to just outright tell the players that "by the way, the journal also has mentions of a fun time the owner had at a cannibalism party last Thursday" but then if the players don't know to ask, how would you tell them?
In real life you could flick through and certain things might jump out at you but without going OTT and making a real journal to give to the players I don't know how you'd do it.
I wanted to use it as a tool to tie two quest lines together as well as give quest B a leg up whilst the players are looking at quest A.