In a Five-Man Band, Power Trio or other ensemble, the characters have to complement each other. One side effect of this is that, in any group of superheroes, no two of them will have the same power. When done well, this can be at best unobtrusive. But if the heroes got their powers from a common origin, or if their powers are granted by technology, it may seem very strange or even like a really dumb design decision. After all, The Power of Friendship is nice and all, but it'd be a real shame if the world was destroyed by a fire demon because the hero with the power of Water was out sick that day.