Professional Fortnite players will look for every competitive advantage that they can use to win tournaments when the stakes are over $8 Million. The new trend is to use a 4:3 resolution to supposedly make hitboxes larger like in CS:GO. So when you watch competitive tournaments expect to see hideous graphics as the screen is squashed and the character models are stretched to give players the competitive edge that they seek. Some say that the increased vertical also gives you the same horizontal view. I think the next step is to start using the 320x200 resolution like Doom used for a competitive disadvantage. Why are players doing it? Because it's an old trick that works in other shooters like CS:GO, where if you stretch the resolution, it stretches each individual character model as well. Stretch the character models, and you stretch the hitboxes, allowing you a larger target to shoot. This is supposed to give a competitive advantage, which is why you see a lot of streamers doing it.