If discipline at home created obedient citizen slaves, the "state" would be all for it. As it is, parents are threatened not just for spanking but any form discipline. My wife and I got threatened by a school teacher once for making our son read too much during the school year. She said it was "abusive". As a parent I say to the state, Stay out of my business, I'm doing the best I can with what I know.
As it is, it looks to me like the state is trying to raise a generation of undisciplined kids that cannot read, write, or hold down a job. I think its easier to enslave them that way.
The end state is that the state will be doing the disciplining (via police and courts). It's not that the state has a problem with using violence to create obedience; they just don't like competition.
the state is for abusing children. they build schools to abuse children, the create the drug war to abuse children by taking away their parent. they let child abusers off with a hand slap.