The story point mechanic, called Destiny points in Star Wars FFG, are a mechanic where there is a token with player good story element on one side and the other side has a GM bad story element on it.
It adds player agency to a story, a universe balanced between good and evil, or to add boost or bane dice to a roll.
The players come to a cliff and for any reason didn’t write rope in their inventory. They can use a story point to add rope to the story.
As the token flips between the PCs and GM it shows that there is an even balance between good and evil in the game universe.
PCs and GMs can use a destiny point to boost the chance of success of a roll and the GM can use it to add a bane roll to the PCs rolls. This can make what is a low probability of success, more then likely successful and what could be easy seem impossible.
There are parts of this mechanic that I like and other parts of it I think can just be part of game play. Like PCs should be able to add story elements as part of emergent story telling and boons and banes should be done as part of telling the story.