I speak to separating parents (individuals as I am not a mediator) regularly as part of my job. I hear very similar accounts and they are often very focused on the parents "rights" and much less on the children.
"I have a right to see my kids"
"I have a right to take my kids on holiday"
"I don't want him/ her to have access to my kids"
If domestic abuse is not a factor, then I try to refocus the parent on the children's rights. That is what should be the first consideration the child's welfare and their "right," to have a relationship with both parents if possible. The rparent may want to dismiss the nrp and not engage with a discussion, formulate a parenting plan etc. as they are angry, hurt, in shock, anxious about losing control of the situation when they are already spiralling.
They want an easy fix, that can cut out the pain of having to interact with this person who has hurt them/ they have hurt.
This includes men who wish to avoid paying maintenance, yet go to court for access, or chuck their children and ex out of the family home, women who want to change their child's name, go abroad, have a new partner adopt their child without the father's permission/ involvement. There are many people who would describe themselves as loving parents and will still act selfishly in the pain of an ended relationship.
So it does not surprise me to hear of a separated father's site full of anger and resentment and very little critical self examination.