This is related to this question. I think we should discourage "Belongs on S[OFU]" type comments. I think they encourage the OP to go to the indicated site and re-ask the question. Flagging/voting to move on the question should be sufficient. Assuming this is the case, would it be proper to flag those comments for mod removal to hopefully get them removed before a new user sees them and duplicates the question?
Or, another example:
Or, even worse, but this new (valuable!) user probably just doesn't know better: