Many have lost their minds with their children. But when parents hit children, oh they're just being a good parents. ARE YOU FUCKING KIDDING ME?!
When a man hits a woman, usually about a foot shorter than them, we despise them. We call them things like cowards, impotent, losers. But a an adult punches a 3 foot child, nobody bats an eye. How much sense does that make?
Firstly, if you hit your child, you obviously don't love them. How can you love someone you hit?
Secondly, you're teaching them that hitting is a good solution, which WAS true pre-1940, but in modern civilized society, violence in almost all situations is a serious crime and can get you thrown in jail.
Thirdly, they're aren't learning anything, except that they can't trust you. The moment you slap them for the first time, you put a barrier between the two of you that is almost impossible to knock down. And what will you think might happen when they're old enough to fight back? Or when you have to depend on them for anything? You think they owe you anything?
Fourthly, you ruin their perspective of gender. A woman abuses her son, he gets, quote "mommy issues"...Mommy issues?! That's feminist propaganda. Let's call it what it is: experience with bad female role models.
Fifthly, children aren't your property. What more is there to say?