I think it would be beneficial, with perhaps slight less "restriction" than the moderator points, for users to have "comment linking" power.
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The procedure would be simple:
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1. find two >=+1 rated comments (or chains of comments) that are:
- Say the same thing
- Discuss opposing views
- Are on the same "sub-topic"
- ... ?
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2. "link" these two comments/chains with a relationship ("Same argument", "Opposite argument", "Related comment")
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3. others now see a list of "Related comments" while browsing.
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Happy to expound as necessary!