In the seventeenth century unicorn's horn began to fall from favor with the educated, though it enjoyed an excellent business among unscrupulous apothecaries. Still, the royalty of France had a highly paid position, the holder of the horn, whose job was to touch the food and wine with a unicorn's horn to test for poison. It is rather unlikely that their majesties believed in any preventive or detective power of the horn, although they may have thought it possible; rather, it was simply an elegant ritual from a previous time, now valued for its own sake. What had begun as a means to prevent violence developed into something with intrinsic worth.
Now, on the Internet, a great many people say a great many things that they would not dare say to someone's face. They do this because they are free from dangers of the physical world, and they argue that politeness is unnecessary and indeed unreasonable, consuming precious bandwidth and time. I would remind them that the graceful rituals of the French court were replaced with the rule of Reason, a time known as the Reign of Terror. We should be careful when we abandon our pleasantries, lest we forsake rather more than we suspect.