I thought the main reason for the 6 again was the constant holding down when defending your line. Im against the rule. Yes I can see how in some instances its better than a penalty fest, but the negatives are just far to significant in my opinion. The clear varying interpretation from officials really effect games. Those variables dont just change from game to game, week to week, they can change mid game. In fact, its fair to say they can, and are easily, ruled differently for the 2 teams playing. I dont think anyone can argue that a lot of games the ref will allow one team a good second longer on the ruck than the other team. This is the really frustrating part and why many people think the game is corrupt. Ref's like Grant Atkins and Ash Klien are without doubt weak humans who favour the top team. They dont cheat. They are just weak and take the easy option of looking after the top team so they win....well I guess that is cheating.
I also hate how you dont have the choice to take a penalty goal. 30 seconds on the clock and the defending team blatantly holds down and you get a 6 again while you are down by 2. Its a joke of a rule.