There is no skill. There is hand-eye coordination, tactics, and strategy. Hand-eye coordination regards your ability to control your avatar. To react quickly to threats, manoeuvre effectively through the map and combat, and reliably hit your target. Twitch response is the bread and butter of modern FPS games, and is usually what people are talking about when they say "skill." Which is not quite right. Tactics are how you play the game on the battlefield. Where you go, who you go with, when to switch weapons, when to grab ammo, when to retreat, when to press the attack. So long as you aren't a blind monkey with a controller, tactics make the biggest different in both PvP and PvE. In a straight shoot-out with equal loadouts the better twitch player will win, but smart players play tactically, and can reliably turn the tables on even the most talented marksman. Play to your strengths, exploit enemy weakness. This is very rewarding to those who can do it. Strategy largely happens before a match. Which weapons you choose to go into battle with, which perks you chose to reroll, which subclass you are using and with which talents equipped. It can be even broader than that: which playlists you enter given your strengths, what social interaction you participate in to pad your friends list with reliable Guardians, and which PvE game types you play to increase the likelihood of getting effective weapons. Knowing your preferred play style and the current meta, you plan your strategy around that information so that effective battlefield tactics emerge from the combined environment of personal loadout + the metagame. The random elements of rewards makes the strategy component of Destiny frustrating to many. We all hate being killed by the same weapon over and over, but using such an effective weapon is the correct choice, provided that maximising your odds of winning is your primary goal (creating an enjoyable experience for yourself, team mates and opponents is an acceptable alternative). It's fine being bested by a slower player with superior gear, that's what gear is for, but an arbitrary inability to acquire suitable counters and alter that experience is less fine. Being denied access to top tier loadouts by random chance despite equal investiture of time and money is a major problem for the game's strategic aspect, and appears to be the primary source of ire for players, especially in PvP and endgame PvE.