There is a difference between using someone's verbatim statements when they have been made in an emotionally heightened state of mind (e.g. in a fight), and using them to vindicate one's self when the blame is being assigned, e.g. in a workplace. There is a reason why the old adage of "give it to me in writing" exists.

Also, even though people may say the wrong things when they are emotional, a repeated pattern of them expressing those sentiments can reveal their real disposition. In this way, a record of what is said, word for word, can be useful to uncover someone's real thoughts. I already do this with my brain, but it is easier when it's in searchable, dated text.