Destiny is, at its core, a very traditional RPG. It eschews the storygame “shared narrative” or “shared storytelling” approach in favor of a traditional GM/player split.
Play involves the GM, who prepares the world, and players, who interact with it in ways they choose, the outcomes of which are determined by rolling dice (“bouncing dice” in the parlance of friend of mine). There’s some interesting “fudging the roll” mechanics players have access to, to boost the dice in specific situations, but all in all it follows the gameplay model first established by D&D, and implemented by hundreds of RPG’s since then.
This is a deliberate choice, not an instance of blindly following the received wisdom. Having read several story-games, and seen how they run in play, I prefer the traditional model.
For me, the fun of RPG’s lies in creating a character, and immersing yourself in that role. It makes the game world seem more real. That’s why, when writing up my settings, I ty and work out the fine details of the game’s fictional world, so there’s plenty of details that make the world come alive.
I also try and give descriptions of what living in this world is like: what is it like to touch a sleeping dragon? To call upon the power of a living god? To smell the stench of a marching horde of goblins? As a player, I want the world to come alive, and as a GM and designer I want to help players reach that state of immersion.
(Or, at least, not actively hinder immersion. Not all players like that sort of thing. Which is fine. There’s coolness in making your character more powerful, or mastering mechanics, or any one of the dozen other reasons people play RPG’s.)
When a player assumes an “authorial stance”, they are by deliberate design choosing to step out of their role. This breaks immersion of character, and ruins the vividness of the fictional world. For me, this wrecks the entire point of playing the game in the first place.
Which isn’t to say that I’m trumpeting a “One True Way” of playing make-believe. People who enjoy story games, are welcome to do so.
Your game, your rules, your fun.
I’m just not one of them, and the design of Destiny follows from that.