It is probably there because the move causes too many hard feelings and causes too many fights. In the 60's I hustled a little pool and played poker and there was a thing in both that we called "the prick factor." Deliberatly pi$$ing the other guy off to get him to make a bad move and put him off his game. It was just part of the game but fighting was not unusual. When I was young and strong it was just one of those things that came with the territory, the poker games were usually in barns or garages in the winter in Michigan. Poker has changed since then but in a live game I still look at it as WAR and not a game. I still have my old two piece birdseye maple Muchi Hustler but I no longer shoot pool.