Lol probably because they want the "sound". I duno if that's the case but in Singapore side kicks and back thrusts usually "push" instead of "deliver impact". In the nationals this year a couple of ppl got flying sidekick-ed and flew to the adjacent arena. >_> not sure if they scored though. As for backthrusts I've only seen one[out of a lot] score, it was a snap - thrust n rechamber.