I am not against downvoting; I know downvoting encourages us to modify ourselves for the better.
However I think that it would be more helpful if it showed us what the mistake is that we made. If we know which points are wrong then we can modify our posts for the better and avoid making those same mistakes in the future. But if I don't know what the mistake is then how can I try to learn from it?
At least a reason should be there to help us improve. Otherwise we will continuously make mistakes.