Let’s say I create an account on LemmyMusic.com because that was the first instance that piped my interest. Later I discover a community on LemmyNSFW.com and I want to subscribe, but I can’t because LemmyMusic decided that they don’t want to federate with NSFW instances? For LemmyMusic this makes perfectly sense, but for my user it might not.
People usually don’t create accounts because they want their data to be handled by music enthusiasts, but because they simply want access to the communities.
Other example, my account is still on LemmyMusic.com but now I want to create a community for a thing that I came up with, it has nothing to do with music, so the only option I have is to create a different account on an other instance that is willing to host my community.
I made a post about something that is related to this. https://feddit.de/post/1033788