I have to concur. Judges chapter 19 to 21 is a propaganda piece written in support of a monarchic system in Israel. In short, is saying: "Look at what happened when there was no King in Israel [i.e. no centralized, unified authority] and everyone was doing what they felt was right in their own eyes [i.e. near anarchy], which resulted in useless wars and massive loss of lives and the near extinction of the Benjaminite tribe".
Although there might have been some truth in the events described [a sexual crime that triggers a civil war in Israel between Benjamin and the other tribes] , the account actually puts Yahweh in a terrible light, for He is consulted in an oracle three times, endorsing the 11 tribes to go to war against Benjamin, and the first two times the Israelites suffer terrible defeats, only coming out victorious after the third strike, and even then, the deaths on the confederated army are vastly greater than the deaths on the Benjaminite side.
Eden