The Benefit of a Short Memory
I can't stay angry. I haven't been able to my entire life. My mother tells stories of me as a child storming off to my room only to emerge minutes later as if nothing had happened. Sometimes I think my wife takes advantage of this fact to win arguments, but overall I consider this quirk a great blessing. I carry negative emotions for relatively short periods of time. I suspect it is good for my health. It also helps me at work.
I often observe colleagues with long memories. I see them burdened by the grievances they carry with them. Even when their project succeeds, it is hard for them to see past their own accounting of failures. It can also be hard for them to accept growth in their colleagues because they so acutely remember past mistakes. At some point the weight of history overwhelms them and they lose touch with the present reality.
Some of this is just loss aversion. People fear losing meaningfully more than they value winning. Much like overcoming sunk cost fallacy, moving forward requires a frank evaluation of the present without indulging the contrapositive scenarios.
Some of this is overfitting. If someone previously made a mistake, it sounds reasonable to expect them to make it again. In fact, the opposite is much more likely. After making a mistake, most people learn from it. In my experience, novel mistakes are much more common than repeated mistakes.
I'm not suggesting we ignore past mistakes. It is important to learn from them. But at some point the value derived from dwelling on a mistake runs in reverse.