Sometimes you need to explain why. If everyone naturally realized they were being yanked about by their emotions and having that used to bypass their rationality, nobody would ever use that technique. This is especially true if you happen to agree with the point being emotionally made. But sometimes when it is pointed out, it is easy to see that you are being manipulated after the fact. It's easy to see why spam should be removed; seeing why this article should be removed is harder.
