If the descentralization of social networks continue, we will have to prepare for the eventual rise of the instances wars, where people will start to fight about which instance is better and which one is weird to be in and so on, but that’s for the future of us all.
The instance that someone is hosted on is (almost) completely irrelevant to which communities they can join.
I am in a local region instance but can still access any communities on Lemmy.world, Lemmy.ml and even other federated platforms like kbin.social
I may be restricted on what I can do in each of those instances; it there is some disagreement between Aussie.zone and sh.itjust.works I may not be able to post about camping to my preferred community.