Children can be free to make some decisions, but his/her parents must guide them to make decisions. They must also take care of the child, and without anyone adult supervision, how could the child stay safe. Parents should also make them have healthy decisions. With out adults, the child could be smoking without them knowing it.
A parents fundamental role as to be the role model, the guide, and to keep the child safe. Why do you think that we have to teach children basic safety; it is because they do not know better. A child crossing the road, without being told would not know to look both ways, when choosing the same concept applies. They do not fully understand what consequences are, let alone how they would affect the child.
Of course a parent should be involved in their children's decisions- that is their job. A child is not capable of making every decision in their life on their own, nor do they have the capability to make safe, healthy decisions most of the time. A parent's task is to teach and guide their child and help them learn what they need to be a functional adult, but also to protect that child. That means being involved.
Parents should not be involved in children's decision because it is children's life and they should step aside . Parents have a big role in children's life but not as a decision makers but as a friend who should guide them with their knowledge and experience and should keep aside with the matters of their children.