I did not read this whole thread but I did read most of it. I think the controversy arises from how severe people perceive a 'doorslam' to be. I know most INFJs don't go about this lightly but a doorslam is still pretty harsh. I have done this in the past but I did not know how psychologically taxing it can be on the other person.
Ancient societies including the Amish would shun undesirables. This would cause the person to slowly start to doubt if they existed and then they would just succumb to depression and die. This is taken to to nth degree but you see my point. Cutting someone out of your life hints at the above. Here's a link that describes some of the effects:
Shunning - Wikipedia, the free encyclopedia