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Don't you think a downvote without a comment, even a 2 word comment, is just unnatural, non constructive and against Stack Overflow regulations itself?
I mean if someone wants to downvote, sure thing go ahead, yet at least give 1 reason for it so that the asker can know why. And if you don't want to comment, then you don't want to contribute, hence the downvote is meaningless and non constructive!
Why don't you limit "down-votes" to be submitted with a comments only? -inside post comment for a down-vote topic arrow-
edite : question splited into two topics ! link