I think it is always easier to argue against something - by quoting ridiculous examples, or citing impossible criteria, than it is to argue for the principle.
May I share a case which I heard of over 25 years ago as a serving secondary teacher. I may be hazy on some of the finer details, but the underlying story will live in my mind for the rest of my life.
It came out in a discussion during a training session on abuse/ disclosure/child protection with respect to teachers.
A little boy of about 7 or 8 came into school on a Monday and in the course of (certainly as we used to do ) writing about his weekend, he said how it had been a special Sunday as he was allowed to have lunch with the family. Alarm bells rang in the teacher's head and at a conveniently private moment she asked him to tell her more about this "special " weekend and why it was different. I would emphasise that the child showed NO signs of neglect or abuse of any sort. He was a quiet, well behaved little boy, clean and well-enough turned out, a bit of a loner, but not especially unusual in any way.
To cut a long story short, what emerged from discreet and tactful questioning was that this boy lived - slept, ate, spent all his time - in the attic. He would change out of his uniform as soon as he got home, put on old outgrown clothes and disappear upstairs. Tea was on a tray and he slept in an outgrown cot with the end cut off as his legs were too long for it.
Wait for it - he had a younger sister who loved a normal life "downstairs" with their parents who were educated, "respectable" employed people with no apparent social problems.
The outcome was that the child was taken into care, later fostered and I believe adopted . The parents were prosecuted of course, but TWO questions troubled those of us there
1) what emotional damage had this poor little boy suffered?
2) what emotional damage had been inflicted on the sister who presumably was brought up thinking it was normal for your brother to be treated worse than a family pet, unloved and neglected in the attic?
If this wasn't criminal, what is?
(I also have since wondered if J.K Rowling knew of this case and was influenced by it when she put Harry Potter in the cupboard under the stairs in the first book of the series?)