Note if two instances are defederated from each other they can’t see each others posts & comments on some third instance
So if people from world and people from beehaw comment on a post here people in p.d can see them both but the beehaw users can’t see the world users (if you check this thread on beehaw theres some comments missing)
Due to this and the nature of this instance the people in different instances interacting with each other hasnt been a problem and its mainly the all feed. As you said people deciding whether they want to join the instance can’t curate their all feed while they lurk so having that not be shit is ideal (and reducing the amount of blocks people need to do)
I found an option when digging through the lemmy code yesterday that allows a community to be hidden so it doesn’t show in the all feed which might be the best thing to do currently. (It just can only be set from the backend and has no ui to set it for some reason ). Still allows users to interact here since that hasnt been a problem and still allows people to sub to those communities. Would have to be extended eventually to be able to cover entire instances and could make it a screen when somebody joins the instance of if they want to see things like politics, sports, etc. which could enable or disable different things to be hidden