In my experience, where the parents are a larger factor in issues, it is usually because of how they reacted to an external event (lack of support, lack of empathy, for example). Often then children have to find their own way through and the ways they learn to do that are not necessarily healthy.
I have seen people blame parents for their bad behaviour. Lack of accountability for their own choice. Believe it or not, people to lie to therapists or omit crucial details, sometimes quite significantly.
I don't disagree with looking at what shaped our world but, once that work is done, the person is responsible for what they do to heal anything. Maybe that does involve cutting some people out of their life. I've seen examples of scapegoating too.
Often, where there is ND in the mix, that can seriously affect communication and relationships, sadly one or more parties may not even be aware it's a factor in play. By the time they realise, if they ever do, it may be too late to heal those relationships with the new understanding of each other.
I could give so many real life examples, but obviously I'm not able to do that. All I'm saying is that it's too easy to blame the parents but to blame them alone is usually not the big picture. Staying stuck in holding parents responsible for everything isn't productive either and can be a way to avoid the discomfort of taking personal responsibility to move forward to a stronger place.
You want parents to take responsibility but it's not all theirs. Yes, there are some parents who should take majority responsibility, but there are schools, peers, workplaces, other family, siblings, romantic partners, clubs, religious organisations, strangers we encounter, neighbourhoods, biology, social circumstances - so many other things. The child themselves makes a contribution to the dynamics at play too. There are a lot of parents of young children confident in their parenting who life will humble when their kids get older. Seen that often too.