Saves time, really. Also I mentioned progression because before then, there were little to no guides released on endgame (unless you did 1.0 and had prior knowledge of Garuda and Ifrit). You were FORCED to learn by doing. Now? Nope. You're more than capable of finding this easily accessible information before jumping into an encounter completely blind. This also saves your booty from the obligatory Scumbag Steve who starts moaning the instant someone has to take a minute or two explaining a mechanic. Even if you learn by doing (I can't really relate, since I learn by observing), it's really helpful for you to know what exactly you're getting into... before you get into it. Since you literally SEE the mechanic before it happens.