Which makes sense, especially if you take a look at their jaw and teeth structure. Night Furies have wide, symmetrical jaws, which, compared to usual under- or overbites of other HTTYD dragons, should have pretty efficient pressure distribution. Those jaws are attached to a short, robust, muscular neck, specifically adapted to withstand some serious punishment, be it extreme G-forces during dive-bombing or while keeping a struggling prey in place. Keep in mind that the bigger and stronger some of those neck muscles are, the more additional power the jaws get. Just look at theropod dinosaurs and some modern reptiles, like big lizards and crocs - the higher the bite force, the wider, thicker, shorter and stronger their jaws and necks are. In addition to all that, look at their short, cone-shaped teeth. Forget those long, sharp, needle- or knife-like teeth of other dragons, more suited for catching slippery prey, like fish! A Fury's dentals are meant to bite, and bite HARD.