Like with everything, none of the both extremes are good.

What helps me in situations where people talk about it for the umpteenth time is trying to drill down and find the root cause with carefully worded questions. I think I might be ready to become a therapist, lol. Though my fuse is quite short due to my own stress so I don't put myself in the "I am your emotional trash bin" kind of situations.

So to me even the situations you describe can be made use of. Think of it as a long-running background task with many steps; after each retry you get a new exception stack trace. F.ex. during conversation #7 you might understand one or two causes of the problem but at conversation #12 you might already have a nice root cause and you can then try to gently nudge the person towards addressing that.

Of course you are not mandated to. It's all about what you need in this current phase of life as well; you don't have to be people's therapist. It's just what I find super interesting the last year or so -- root-cause analysis of human problems.

But when I understand that somebody just wants to whine and be a constant victim, I mentally check out. Not worth the joules that my brain would spend on that person.