Related: https://github.com/LemmyNet/lemmy/issues/2012
I think the devs want comments to be specific to the community in order to retain the culture of each community.
https://github.com/LemmyNet/lemmy/issues/4225#issuecomment-1904443026
Combining comments is out, because these are different posts that live on different communities, each with their own members and mod policies.
Lemmy-ui already has a "post-deduplicator" that simplifies viewing cross-posts on the same page, that should probably be replicated in a lot of UIs. But that seems to me the best way to handle it.
This comment is another way to explain the issue https://github.com/LemmyNet/lemmy/issues/4225#issuecomment-1837522660
This would be a bad user experience for certain communities. Imagine the same news article is posted in /c/cars and /c/fuckcars. It is not desired nor expected to have all comments combined.
But I do think there may be some room for combined comments, like when Lemmy has a method to group communities, maybe those comments could be combined from the grouped communities.