Correct, it seems to only happen when there's a number of them from a single world. When you are used to staying at home, then you want to have a home. Many of them were teenagers: in fact, the two who originally created this were teenagers from the same world. They wanted to create a home for them and their friends, so this is the result of that desire.

I have always had trouble with it myself being a general from my own world so the concept of home is lost on me. My country was my home, therefore Johto in it's entirety is considered as such in it's place.