I just found out @Midwest.social exists after finding the Chicago community there. I was trying to list out other communities on that instance and couldn’t quite figure it out. Do I have to visit Midwest.social in order to list them, or is there a way to do it from lemmy.world?
Instance A does not know about the existence of instance B until some user on instance A requests a community from instance B; and even then it doesn’t know about all the other communities on instance B.
By analogy with email: You don’t have George Bazooka-Smith in your email contacts, because you’ve never sent or received email with him.