I proposed an extension of the feature set. The current behaviour is still possible. You can use the added feature but you don’t have to.
The issue for me: The current landscape in lemmy has a lot of sparsely filled groups - I do not browse by group (filter by subscribed or all and sorted by new or hot).
In this view multiple identical posts with distributed replies are shown. This adds redundancy in the comments and reduces clarity.
Edit: The idea rises the question, how the ownership (or relation) of a post to the group and its replies should be handled. Using an x-post-like approach is just one idea.