That you need to do things in one, single particular order in order to finish your quests or be able to get certain dialogue triggers, like romance options unless you pay unreasonable attention to doing things in just the one, right way.... like developers assuming the party will rest in camp before entering the grove and therefore cutting some camp dialogue because of it. Makes no sense.
DOS2: You can go anywhere in this Act, but the levels are arranged in a single viable path, with a heavily implied order for the story.
Remember the human (This is a forum for a video game):
