Well, this is about savage, not level 14 content. When you're at the point where you're doing savage, there isn't much room to "gradually improve over the years" anymore, because the skill ceiling is very low and simply reading a job guide (which anyone hopping into savage should do) will have people damn near hitting that ceiling in weeks, not even months, let alone years. Because everything is static PvE and kits do not interact with each other or anything else aside itself, learning this game is very fast, as it is rather shallow.