Not paranoid but I have actually had dd's former school report us to SS not once but repeatedly as a way of punishing us for dd's frequent medical absences. Fortunately, the SWs who came to see us were sensible, level-headed people whom I could talk to- but each time I couldn't know that until the individual actually turned up on my doorstep (the EWOs were a bit more variable
).
And even so, being investigated did do some harm to my dd, despite all the sensitivity and genuine professionalism of the SWs involved. I think it would be nice if all professionals recognised that just because the child has not been taken away, she has not necessarily escaped unscathed from investigation and that she may need counselling or extra support afterwards.
Dd for many years knew that telling an adult outside her family that she was unable to perform due to pain was likely to bring down another investigation and another string of suggestions that there was something wrong with her family.
Those who would shrug their shoulders and say "no harm was done" are not the ones who have to deal on a daily basis, many years later, with a child who would rather cut herself so she cannot go to school than go to school and have to explain that she is in pain again. Let's put it this way- the local CAHMS are not suggesting that no harm was done 
Of course SW have to investigate- just like surgeons have to operate. But like an operating surgeon it might be wise to recognise that you leave a scar behind, and you need to take care so that scar doesn't get infected. This is not slagging off SS any more than I'm slagging of my doctor by pointing out that my caesarian left a scar. Both were skilled professionals doing the right thing. But both left scars.