I agree that venting is probably about re-enacting the event, but with a particular purpose: to change the past. By addressing your complaints to an invisible mute adversary, you get to tell off the subject of your ire and feel confident that they can't fight back, and validate your own feelings.
The closest thing I could relate it to is domestic violence. When a man comes home from a frustrating day of work and beats his wife and kids, he's not just fulfilling a sadistic desire. He's projecting his work troubles on his family, and by assaulting them, righting the perceived wrongs he suffered. Venting is, imho, a version of this, but without the intent to harm.
Yes, I think I can agree with the idea the goal is to change the past. However, this just further leads you down the rabbit hole, since now in addition to being angry about the event, you're also angry about your inability to change it.
The closest thing I could relate it to is domestic violence. When a man comes home from a frustrating day of work and beats his wife and kids, he's not just fulfilling a sadistic desire. He's projecting his work troubles on his family, and by assaulting them, righting the perceived wrongs he suffered. Venting is, imho, a version of this, but without the intent to harm.