A physical response is no deterrent, at all......especially in the modern game. A PP that scores 3 or 4 times for every 10 pp's is going to put the brakes on opposing teams much quicker than jumping someone and not only taking your team off the pp, but likely getting you an instigator on top of that.
If it's a meaningless game for the pp to settle that score in, how is it a meaningful gesture to fight? If Petey and Co are punishing teams on the PP in the pre-season, I guarantee you other teams are noticing