Ok so different instances have different rules on who and how communities can be created
some require that you ask the admins, and they create it and give you mod priveliges.
some allow you to create communities on an ad-hoc basis.
some only allow admins to create communities and give no mechanism for users to do so.
Generally you can only create communities in instances you’re apart of, but you can be given moderator privileges for communities across instances, provided the admins of the instance where the community allow it. If you don’t like the community creation requirements of a server? Create an account on another instance and start a community there.
Community names are unique only to the instance they are created on - meaning you might want to do some research and check if the community already exists on other instances.
Otherwise redundancy means different versions of the same community on different instances can have lightly more or less palatable rules and moderators, therefore catering to different people of the same group.
There is talk of adding an option to, on a per user basis allow an option of browsing a combination of communities across instances at once. But it’s hard to say whether this should be incorporated into the backend as an API addition or to let the various frontends implement it based off of the data they can already get from the API.