I'd proposed a potential solution.
I'll paraphrase : Currently, every Lemmy instance (ie: Lemm.ee, Lemmy.world, etc) is an island. This is one of the strengths of Lemmy (Federation) as we don't have to worry about information being restricted, censored, manipulated (ie: Reddit).
However, as things are currently, this Federation comes at the expense of splitting the community between instances. asklemmy@lemmy.ml vs asklemmy@lemmy.world is a perfect example. Posts are either duplicated (which creates noise) or it fosters a "Lemmy instance death by starvation". Meaning, more and more conversations will eventually drift towards one of the two asklemmy communities, leaving the other one to "starve out". This defeats the entire purpose of federating.
There has to be something better.
For example, instead of “every instance is an island”. Meaning the current hierarchy is “instance” - > “community” - > “post” - > “threads”. We could instead have “community (ie: asklemmy)” - > “post (ie: this post)” - > “instance (Lemmy.ml, Lemmy.world, etc)” - > “threads (this comment)”.
From a technical perspective, it would mean that each instance (that's interested in hosting this supercommunity) would replicate the community names and posts (Not the threads).
Lemmy already kind of does this, when a user pulls a post from another instance. For example, I'm on lemm.ee but when I view posts from asklemmy@lemmy.world, lemm.ee will retrieve and cache it on lemm.ee. As long as each instance would share a unique identifier to associate the two communities/posts as “the same thing” (and this could simply be the hash of the community /post name). Everything else would be UI.
Each instance would take ownership of the copy of the community and post, which means they could moderate it according to their standards.
As an end user, you'd view a community and post, but the comments/threads would be grouped by the instance that hosts it. If there's an instance you don't like, you simply unsubscribe from it.
For future iterations, it might be nice if the instance itself would auto-subscribe or suggest other instances that host the same community to the user. Meaning, if I subscribed to asklemmy@lemmy.ml, I'd automatically be subscribed to asklemmy@lemmy.world. However, as the user, these are all separate subscriptions, so I can customize it as I see fit.