This depends on exactly how you interpret this statement. If it means “good parents ALWAYS prevent their children from making mistakes,” it is false. If it means “good parents SOMETIMES prevent their children from making mistakes, it is true. In general, I believe that good parents allow their children to make mistakes in areas where mistakes will not badly harm them, but they do not allow their children to make truly harmful mistakes.
I believe that children need to learn to make their own choices. This means that they must be allowed to fail at times. If they are never allowed to fail, they will never learn to deal with failure and to learn from their mistakes. Therefore, I believe that it is good for parents to let children make mistakes like staying up too late, spending money on stupid things that they will regret buying, and turning in substandard work in elementary school or even middle school.
However, good parents do not allow their children to make truly grave errors. If they can prevent it, good parents do not let their children give out information over the internet that can allow a predator to target them. If they can prevent it, good parents do not let their children drive while intoxicated. These are the sorts of things that can end a child’s life. A good parent cannot allow them to happen if they can be avoided.
Thus, I would argue that a good parent allows their children to make some (or even many) mistakes, but does protect them from making mistakes that could cause real harm to them or to others.
It really depends how you intpret "good". Some may say it is being kind to your children or raising your children in a well manner. So the answer is yes and no. "Good" parents do try to protect their children from making bad decisions. Although, they might not always succed. As children get older, they start to rebel (some, not all) and become independent by making their own decisions. Not all their decisions may be good, but the parents cannot stop them. Good parents would like to protect their children from mistakes, but are not always sucessful in doing so.