Lets take monster hunter for example. Everything in that game is based on luck, but if i want to get that Rathalos Ruby with 1% drop my skill can increase my odds. I can cut the mobs tail off for a chance for a drop i can capture it for a chance of higher drop, or make it drop an shiny item for a chance for it to drop. All of those things require player skill to get better drops. No matter how good i am @ AV,CC it wont make the RNG any better.