Yes, it is true the publications never approve spanking/violence towards children.
I don't mean to be a pest, but that is not quite accurate. Publications definitely encourage corporal punishment. Maybe the newer ones do not--I don't know--but the older ones definitely do. Here is one few example. I believe the old Great Teacher book and Your Youth--Getting the Best Out of It both state it is a parent's obligation to spank their children.
Watchtower 1954 January 15 pp.54-62 Disciplining Children for Life ***That brings us to discipline, and forces a facing of that hotly controversial question: to spank or not to spank.
2 Many child psychologists put a "hands off" sign on children, as did one who said: "Do you mothers realize that every time you spank your child you show that you are hating your child?" Jehovah says: "He who spares the rod hates his son, but he who loves him is diligent to discipline him." A spanking may be a lifesaver to a child, for Jehovah says: "Do not withhold discipline from a child; if you beat him with a rod, he will not die. If you beat him with the rod you will save his life from Sheol." Again, "Blows that wound cleanse away evil; strokes make clean the innermost parts."...But to help us get to the bottom of the matter let us look at the animals that you children love. Jehovah's wisdom is reflected in his creations, so to look to animals for instruction is not to lower our thinking to their level, but to lift it to God's thoughts... There is no juvenile delinquency in the animal realm, because there are no delinquent animal mothers. They do not spare the paw and spoil the young, but spank to preserve the young.