I think that you would agree with me that the Bible is our sole source of Truth, and is good for education, correction and training.
In the Gospel of John, Chapter 21 and verse 25, we read that "Jesus did many other things as well. If every one of them were written down, I suppose that even the whole world would not have room for the books that would be written."
With all of these events, miracles and stories to put in to just one Book (the Bible), "why" did the Lord decide to put this particular story in it?
Could it be that there are certain principles and lessons that He wants you to learn and apply in your life?
And, could it be that these events, miracles and stories are much more than what we might remember from our Sunday School Days as a young child?
David had refused to accept responsibility for the actions of his men. David's lack of responsibility allowed a spirit of sedition to come upon Absalom that would lead not only to Absalom's death but the destruction of David's ministry.
His refusal to hold Joab accountable for deceiving David and going around the king's authority and killing Abner in alleged retribution for the death of Joab's brother provoked unforeseen consequences.
While it seems that life went on and there were no extending consequences to David's lack of accountability, there were. On the sidelines, David's son, Absalom watched his father rule without authority and do nothing to right wrongs inside the kingdom as well as inside of David's own house and family.
David's decisions and the way he refused to be responsible and responsive as King, led Absalom to rebel. It would be this visual of injustices that would lead Absalom to challenge David's throne.
This is David the Ministry Years (Part 2): Follow Me and You can have our Own Ministry" episode.