There is a quest that teaches this early on, it's a whole thing about having to invest a point in getting it.
I think alot of people are just not reading everything, but it's because the game is info overload, it tosses so much shit at you, the UI is awful, and it's also loud and obnoxious. While you are learning and trying to figure stuff out, the game is tossing multiple screens at you, loot rewards flying at your face, and you have the game playing out "funny" dialogue. It's really hard to focus on what anything does with how much is dumped on you.