Questmarkers are as convenient as they can be poisonous. They can easily ruin the exploration part of an RPG, diminish good writing and make interesting quests boring.
‘Cause it seduces to →Skip and →Skip ….
But, I think, Questmarkers aren’t per se corrosive, it is the automatic setting of markers on persons and locations without prior interactions with them.
The ability to mark important persons or locations manually or semi-automaticly after an interaction is still valuable and could reduce annoying searchings (e.g. on a big city-map).
An important task of markers (often in conjunction with automatic journal-updates) is to preserve informations of a quest, because, well, we aren’t kids anymore and there will be weeks or months without the option to play the game.
Automatic journal updates are good enough for short and simple quest as in “Augury of Chaos” (or… it is probably the best option for this kind of quests.)
But if there are complex quests, perhaps over several maps or chapters, automatic journal updates attract the same problems as typical MMO-Questmarkers: They tend to disengage the players emotionally and intellectually from their tasks, because they are only superficially involved in them to begin with - while there is sill a lot of mechanical work to do.
For example a complex detective quest with deceiving, conflicting and superfluous informations: if the automatic summary is enough to make the right decision, then obtaining these informations is diminished to running and clicking on NPCs. But if the automatic summary is not enough, then the player, who can’t remember the details, because he was forced to pause the game for a prolonged time, has a problem…
Fortunately there is a solution: Allow the player to copy every text to his journal, be it conversations, books or notices, and give him the option to assign these texts to the specific quests (or to “general lore”). So all informations are preserved, while it is still the player who has to sort and evaluate the obtained informations.
Of course, this is only important if there is the intention, that the new modules have complex quests. AoC is good as it is and there is no need to change it.