True and I completely understand these grey areas, that what makes the game so hard to umpire. But I'm not talking about fending off, it's that particular motion where the player tries to sling the arm of the tackler above the shoulder, i.e. the Joel Selwood technique.That's what I mean by it still having plenty of grey areas.
With regard to raising the arm, footy players are taught since juniors to raise their arms with impending contact to help free the arms to dispose. Additionally, you'd be outlawing any action to brace against or fend off opponents. Banning those 3 things are absolutely against the spirit of the game. Surely the benefit of the doubt should go to the ball carrier and the onus be on the tackler to lay a legal tackle.
These issues I'm raising are some of the ramifications on rule changes. I have no doubt that if the AFL applied the suggested changes as put forward by Bigfooty, these issues would occur and people would bitch, moan and complain about it.