This is part of the reason. Indeed, this is the first reason given, but it is not the only reason. Nor must they obey this commandment of God because they fear dad's punishment. Chastisement is a deterrent to disobedience, but it certainly is not the reason for obedience. And yet it's not infrequent that this is the reason given by children.
Children honor their parents because they are thankful.
Children of God honor and obey Him because they are thankful for their salvation. Children, honor your parents because you are thankful to God for everything He is for you. Especially, they must honor their parents because their parents are over them in the place of God. These reasons show how serious dishonor is. First, dishonor shows that children are not thankful, do not love their parents.