Instructions unclear, post wasn't ignored.

I am still trying to wrap my head around how it all works, but I feel like I am slowly getting the hang of it. One thing I was wondering, and forgive me if I get the terminologies wrong, since instances are their own little ecosystems, wouldn't there be multiple versions of the identical communities i.e. gaming, videos etc., or is that the beauty of it all?

Another minor concern I have is that since instances are run by individuals, wouldn't there be a risk of losing massive amounts of content if said owner no longer wishes to maintain their instance or "goes rogue" for a lack of a better word and shuts down access to all communities located on that particular instance/server.