Why did the Promised Messiah (AS) say that beating small children is a kind of Shirk?

Just one line from the 2 min video answer of Khalfa IV, Mirza Tahir Ahmad (RH).

If people do not pray to God during their upbringing of their children but mainly rest on their own beating and force, this is a sort of Shrik. Because they depend not on their prayers before Allah but on their own might over a small innocent child.