Inevitably, after a while, you get people losing track of things that were actually said, that were actually agreed on etc because there are no documents or that kind of tracking for that matter (there is stuff in Jira, but that's only following the hard tech points, not all the rest that was also discussed).
My business partner and me write a lot but we know nobody is going to read it; we do it anyway because I don't want to end up with a feeling of insanity in yet another phone call with 'but we did not discuss that!'.