The "Move this message up" feature is not intended for moderation.  
It was developed to prevent users who have the right to comment on messages from leaving a comment without content for the purpose of moving a message up.

When a message is commented on, it does in fact move up in the feed so that users can see the latast conversations first.

Writing "⬆️" or "up", for example (which is common practice in networks with this type of feed classification), is the same as clicking "Move this message up" without polluting the feed.

 

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