Fundamentally print developers are no different than film developers in their mechanisms of action. But with print developers we are concerned much more with tonality, color, and a relatively short developing time than the graininess and sharpness characteristics that often concern us when chosing film developers. The reason is simple - you don't enlarge the print. So the same way we don't worry about sharpness or grain when developing 8x10 film, we don't worry about it when developing printing paper. The adjacency effects referred to in this thread are immaterial unless there is a significant enlargement/magnification factor.