If everyone was spread out onto different instances, and communities were based all over the fediverse, the decisions of one instance would be less impactful.
Correct me if this is already a thing, but it would be nice if you could post to multiple communities at once and have users see comments across all communities and instances. So a user posts “A” on instances X, Y and Z all under communities run on those instances at the same time. When making the post, you select ehich communities the post goes to instead of just one. Users on instances X, Y and Z see it as a single post it appears in all of the communities the user specifies. A limit might be useful here to prevent trial spam. A user commenting on the post in instance X will be seen on the other instances and communities where that post was made.That way, you could remove the centralisation on instances and communities (one community or instance might remove the thread, but everybody else still sees it and each others comments in the remaining communities/instances.) This has a few advantages:
People are incentivised to post to smaller communities knowing that larger ones will also get the same post and everybody can see each others comments.
If a moderator of a community removes the post, it still disappears in their community, but not the whole instance. If the thread still exists in other communities in the same instance, users of that instance can still participate in the post on those communities.
If the post is banned instance-wide, it is banned across all communities in the instance at once. This could include non-local communities.
Users in other instances will still be able to see the post and continue contributing to it. You can only remove the post from your own instance.
One issue that came to mind when I tried to re-write this comment to post it on lemmy_support: a post can be made to communities with completely different rules resulting in commenters following the rules of the community they are in, but not the other community the post was sent to. This seems like a pretty big issue for moderation.
That is why defederation and blocking communities happen! If both communities are on far extreme side of the scale then there's no good ground to be made for interaction.
Only idea I had in mind would be to have the post go to a "home" community and all other communities pull the comments from that one and submit their own comments to that one. If the "home" community has rules that the others roughly follow that might help filter the extreme ends out so you don't just get constant de-federation.
Content allowed on instances:
Instance 1: Content A, B
Instance 2: Content B only
Instance 3: Content B, C
By making instance 2 the home for the post, which by it's own rules only allows content that both instance 1 and 3 allow themselves, you filter out the content which 1 and 3 would hate. Of course, this puts the moderation burden on instance 2. You could still allow instances 1 and 3 to have their own comments which instance 2 doesn't allow, but only they will see those comments.
IDK, I feel I'm starting to see why Lemmy works the way it does. I'll post in !lemmy_support@lemmy.ml if I get a better idea. :)