A coordinate system is an abstraction, whether anything has some large coordinate is irrelevant to the coordinate system itself. But my understanding of MWI is that there is discernible state being described by the Schrodinger that is taken as "real" or "concrete" by MWI. If we considered the non-actual branches as merely abstract coordinates, then there would be no problem with profligate state and its associated theory cost. But then it wouldn't be many worlds, but rather some kind of collapse theory.