The difference here is that Dwilight began with a one character limit so no one has ever been forced to choose which one of their long-standing, developed characters they'd have to move to some other place.
We've gone round about this issue on the D-list a bunch of times. Not every instance of two characters on an island are "second" quiet characters, realm control robots, or power props. And there are /a lot/ of instances of Families having two characters per island.
