Kids don't want to learn how to check at that age for the most part(meaning checking properly, they obviously want to hit). Their skillset is undeveloped, and taking checking out of the game until they have a solid grasp and the cognitive ability to understand when, how and why bodychecking is allowed in the NHL I completely agree with Alberta's decision. All it takes is one kid to not know the skill to make an huge negative impact. Even if 95% of the kids could hit properly, there is still going to be situations where checking from behind, elbows etc. get up because the kid doesn't understand the consequences of the play. That's not even mentioning the fact that even legal checks can severely hurt a young player. There is still a lot to teach kids about the game, teach them to be strong on the skates along the boards, teach them how to protect the puck, teach them how to cycle, just because you can't lay someone out doesn't mean you can't teach the player to be strong on the puck during battles and to protect themselves.
I understand that some want kids to learn how to protect themselves at a young age, but in my opinion that's like letting a kid drive a car immediately off the lot and just let him learn as they go, putting other people and themselves in danger. There is a reason in society that responsibilities have to earned over time, and I don't see why hockey should be any different. Kids hitting each other put them at more risk, because their mind and body is still developing, and concussions can happen from perfectly legal checks. I don't see why any parent would be against this, but then again I'm just a 23 year old.