Any reason Reddit isn't exploring peer-to-peer image caching? Given how much time folks stay on Reddit and the disproportionate amount of traffic going to front

Any reason Reddit isn't exploring peer-to-peer image caching? Given how much time folks stay on Reddit and the disproportionate amount of traffic going to front page posts, when an image gets to the top, there should be tons of user connections open to allow for peer-based caching.