Sigh...dont be so ignorant, do what I do, tell them to **** OFF. They aint part of your world. They aint gunna expand your world, they will only crush it.
Well, then dont. Your world is small and the only way to increase its size is by befriending others and entering their worlds to expand your own. Theres worlds you may like, and theres the ones you dont like. Its up to you on which ones you end up using to expand your world.