I think duplicating posts is fine in this case. That is, links can be shared on multiple link sharing sites without infringing on the original creator.

Pure comment threads not based on a link could be hard for now, particularly with the fragmentation between tiny emacs communities on lemmy. It would be nice to have regular tips and tricks threads, or ask anything threads, but there needs to be enough of an audience for those to work, and limiting the frequency with which they're posted might not work if most users are sorting posts with a recency component in the sorting criteria. I don't know that trying would hurt, but it might take a bit for participation to grow.