What functionality is missing? What is unsatisfying with the current situation?

  Currently, co-author slots are universal across all of your worlds rather than by world. However, if you have the same user added as a co-author in multiple worlds, they count against your co-author limit for each world.   For example, if you add Jane Doe as a co-author in both World A and World B, two of your co-author slots are taken.   This makes is counter-intuitive and makes it very frustrating to collaborate with the same people across multiple worlds.   Please either: A. Make the co-author limit on a per-world basis rather than on an account basis. - Ex: John Smith has a Master guild membership and has created two worlds: World A and World B. World A has 4 co-author slots, and world B has 4 co-author slots. Jane Doe is added as a co-author to both World A and World B, and takes a co-author slot for each world, leaving World A with 3 remaining slots and World B with 3 remaining slots.   Or, B. Make it so each unique user name only counts against the limit once - Ex: John Smith has a Master guild membership and has created two worlds: World A and World B. John Smith's account has a co-author limit of 4 accross all worlds. Jane Doe is added as a co-author on both World A and World B, and takes one of John Smith's account co-author slots, leaving 3 remaining slots across all of John Smith's worlds.    

How does this feature request address the current situation?

  It is counter-intuitive that the co-author limit is across your entire account, and yet when you add the same user as a co-author on multiple worlds, they count against your limit for each world they're added to.   Changing the way the co-author limits work to either be per world or only count unique usernames would resolve this discrepency.   It would also make it easier to collaboratorate with the same people across multiple worlds.  

What are other uses for this feature request?

Supporting game development teams working on multiple projects using World Anvil as their world bible & narrative wiki.