These small details of having posters or writings on the wall giving you hints on what you can do where a lot more diegetic and inmersive than having the HUD guide telling you what to do
These also were audio cues, character quotes, the iconic power arrows, signs, lighting that highlighted a important element on a room, etc
It incited to exploration, to navigate throughout the map, to look for more hints, to be more curious, to use your common sense.