A couple of funny memories on this...
I remember talking about this with senior refs when I was a kid (I ref'd little kids when I was a teenager). They would specifically teach you that even though there is no offside, you can still be penalised for an intention forward pass in your own in-goal, and that they had recently added a rule to outlaw deliberately heading the ball to your teammates. Given that many rules are made to close loopholes, we all speculated that somewhere out in the bush their was a team running around winning games by heading it to each other - and someone complained.
I was also at a Qld Reds game years ago (corporate box; I would never pay my own money to watch that sport) when Quade Cooper kicked it across the entire length of the in-goal to the winger on the far side. They ran 90m and almost scored. It was one of the most insane things I've ever seen on a footy field. I reckon the Reds coach would have thrown his latte at his au pair.