The whole you'll regret it/ only get one mother and father/ I'd give anything to have mine back just demonstrates how stupid the person saying it is. You're lucky if you have ever had the type of relationship where you'd regret it or mourn their loss.
I'm also sceptical about those that think it's sometimes over trivial issues. As well as it often being the final straw, other people's idea of trivial can be very different to the reality.
My childhood was materially privileged and very abusive. I've made the mistake of opening up to people only to be told it wasn't real abuse because emotional abuse isn't that bad and I should count myself lucky I had nice shit and wasn't knocked black and blue. As a child, I often wished that was the reality because more people would have noticed, people would have believed it abuse worth reporting and ss would have got involved.
As to those nc with several family members or all, it doesn't take much imagination. I was an only child, but I've talked to plenty of people with a similar experience to mine, but with siblings treated completely differently, or a golden child sibling. And yet even if the siblings acknowledge they had very different childhoods, it's quite often them that pressure the abused dc to forgive and forget and join the parent in trying to minimise the past. It hardly requires a degree in psychology to understand why the victim would need to go nc with the lot.
@Fuzzyjumper
Thing is, when you've experienced your own parents not even liking you, whether some random new acquaintance or colleague approves of you is irrelevant. If anyone was cautious about me because I had an abusive childhood, I'd just think they were a bit of a twat and carry on with my day. And possibly amuse myself by playing up to whatever stereotype they had conjured up.