Some people need closure, some people don't... I think it depends on their ability to reflect on why the relationship ended for themselves
Giving someone a list of all the reasons you don't want a relationship (what you don't like about them in essence) doesn't feel kind, so that can be hard
Depending on the personality of the person you are giving closure too, they may not accept it or agree with it and that can cause more distress to them when the relationship is over regardless.
Closure may have been coming for a while before the relationship ended but a person's determination that a family relationship is something that doesn't sometimes end, may make them less able to understand that the reasons have been shared already
In essence, sometimes it depends on personality type, a more controlling person has a greater need for direct closure, someone able to self reflect and look back on the times things were distant or emotional may find it for themselves