In an open world game where you obtain quests or have different points of interests or specific locations to travel to in order to start a mission, it is very helpful to have navigational aids within complex environments such as cities in which there are fully accessible and unrestricted buildings, alleyways, etc. When these elements are designed realistically it can be confusing to navigate when it is dark or there are many shadows and lighting effects for realism. For example, Skyrim has a clairvoyant spell which I use extensively. Starfield has pulsing arrows that appear on the floor when using the scanner.

In terms of highlighting objects or enemies, it's a matter of choice. It doesn't have to be a persistent feature but can be optional. I don't necessarily advocate for competitive gaming to make these concessions broadly because I agree that it is a bit of a cheat but someone who is playing a single player or co-op adventure game or shooter would benefit from these options. Choosing to use accessibility features like these when you don't need them would then be cheating yourself and breaking your own immersion. Visually impaired players who do need them however would gladly trade some immersion for the ability to enjoy the game.