Hopefully a brief summary of a scene from an adventure they publish.
The party finds themselves in the only inn catering to their type of people with empty rooms in the last town before a vast wasteland. The dinner served is overy salty and heavily spiced but the mead is thick and hearty. That night as they are asleep, one by one they start to get sick (making Con saves), the food it seems wasn't poisoned just spoiled. The first character to succumb to the sickness will find at the end of the hall are a couple small privy chambers. The innkeepers have decided to rob from these glory hound treasure laden adventurers as few notice when they disappear, in an alcove behind the privy they wait in hiding with garrott in hand. As the second hero succumbs to the uncontrollable diarrhea he finds only one empty privy, guess what happens to him? The innkeepers literally catch our heroes with their pants down, kill them in a way they can't yell out warnings, and have a secret hall way to drag the dead bodies in so they can continue doing this all night long.
Now is there more to it than that sure, there are magics involved in everything but the spoiled food, do the inn keepers have even more surprises and tricks up their sleeves, yes they do.
But I think you get the tone, to survive you have to roleplay. The cleric casting purify food and drink stops the ambush cold, one simple first level utility spell while saying grace before your comrades eat dinner and everyone lives. If not having a buddy system, or maybe being in a romantic relationship with a fellow party member and sleeping in the same bed makes you want to comfort them or check on them, stops it before to many bad things happen. But if the players only think in terms of what combat spells to prepare and what might come at them on an even playing field or in a balanced encounter then you could end up killing a few of them.
That is just one encounter in one book, but stuff like that is spread throughout their products. Not just save or die things, things that make you think and make you roleplay or you are screwed.
Did you not talk to people in town and get rumors and vital clues? Well guess what the entire adventure just got that more difficult because you party choose to only talk to the guy with the "!" over his head.