bringthepiecesbacktogether asked: There are many cards that could fit in less colors than they are actually made in (Detention Sphere is UW but could be W, Siege Rhino is WBG but could be BG). Is there any reason to do that other than balance and flavor?

If three color cards had to always have a unique quality of each of the three colors, you would see very, very few three-color cards.