It's quite sad IMO, don't recommend to go there unless you want to have a bad day reading about the most horrific work environments and bad practices in the world.
It's not supposed to be negative per se. It's supposed to be entertaining.
It's an art form. It's not everyone's cup of tea, just like horror isn't everyone's cup of tea. But people often watch horror movies for catharsis, not because they want to be depressed and wallowing in self pity.
Storytelling is often about educating people about things you can't speak about more directly. It's often a way of sharing wisdom in an inoffensive manner and one that will stick because people will actually pay attention, unlike when you are giving them some dry lecture about some problem they haven't yet had and don't yet care about.
But if you entertain them, they will read it anyway and that story may stick with them. And then six months or a year later when they have the same problem, they will actually remember how someone else handled the same issue and it will turn a potentially nightmarish scenario into "Meh, I just did the same thing that guy on Reddit did to his shitty boss/customer/coworker. Worked like a charm. Moving on."
This is literally the basis of human interactions, thats how we humans work at every scale to form friendships/families/societies/nations.
It just stated that the specific pressures and rewards present in most reddit communities tend to encourage this specific style of writing.
The flair for the piece is "Rant." That's an official category for the sub. There are going to be expectations surrounding how you write when using a tag like that.
Just like Hacker News! Here's a clue--it's in a subreddit where these types of stories are welcome.