Why cant your friend move to your town in Animal Crossing?

You can, ok so say the friend was moving to YOUR town you go on Immigration amd you friend goes to the Town Hall and tells Pelly or Phyllis they are moving and they shold come into your town! NOTE! IF YOU OR YOUR FRIEND DOES THIS THEN YOU FRIEND WILL HAVE TO PLAY ON YOUR ANIMAL CROSSING TO GO ON HIS/HER CHARACTER BECAUSE HIS/HER CHARACTER WILL BE GONE ON THERE ANIMAL CROSSING, THERE WILL JUST BE AN EMPTY SPACE! Just thought you might need to know. xD