Maybe instead of adding a comment, you could also have a button to add another link covering the same topic. Good for when someone links a BGR story that's just a linkbait headline summary of a BI article that's just a rewrite of a NYT interview. So let's say all articles for a common topic become linked. Allow upvotes on articles and the highest one becomes titular for the meta-thread.

This would (1) condense topics so the front page isn't deluged with say 5 twitter api threads, (2) unify discussions and avoid repetition, (3) help enforce good net practices i.e. linking to the best source.