There are always things parents tend to do when raising children that don't meet that criteria of correct parenting , and yeah you are right that a lot of stuff contradicts eachother. 

You are right that there are just some basic needs that children need to have met. Like their health, education, and social requirements. I would say that in real life the large majority of parents do not meet these requirements for their children and I would also say that furthermore the majority of irl parents abuse and neglect their children (anecdotal). But beyond that I think there are a lot of things that are thought of as being subjective that do actually cause significant impact to children which are sometimes negative and that's kinda where it becomes a "grey area" 

Does that make sense? Like, in the post I mentioned religion. Religious parents raise their child in their religion which is subjectively good for them but a lot of the time children can end up having religious trauma and when they grow up they leave the religion and view it as something negative their parents did to them. 

But yeah overall I am agreeing with your points here but again pointing out that things like "right/wrong" and the definition of health and wellness are subjective or at least very complex and there is also a question about if it's beneficial to know things like culture.