Because it says it is perfectly ok to do what he did.
Men have been beating & killing their wives since marriage began
And some religions and cultures think that is fine and others do not.
He belonged to a religion who says it is fine and lives in a culture that says it is not.
The habitual (non-muslim) wife beater thinks it’s perfectly fine too. Try visiting a battered women’s center and you’ll hear some revolting stories - like, he beat me & broke my arm because he didn’t like the dinner I made.
Torturing women, mutilating women, and honor killings have been going on since the days of Mohammed, the child molester. Why should Deerborn be any different?