LOL, OMG you made my day with this post. LOL. First, every hour of the day on MR, after the first couple of posts, the thread ends up going OT, so much so that I've forgotten what the thread topic was about.
Secondly, you should check many threads, I can't count how people just love to talk about themselves and their personal lives on MR. They'll start a thread asking for help on a problem they have, but first they'll start off by telling us that they took their GF out to lunch or they were hanging out at the mall eating pizza while thinking about what they are planning to do the rest of the day, then after a full paragraph of their life story that nobody frickin' cares about here they finally get to the topic at hand.
Oh, and my favorite ones, "The Spill on Keyboard threads". The OP will start out telling the forum that he was drinking coke while reading his favorite book or a text book for school because he has an assignment deadline, he reached to turn the page on the book......dadadada...and then when his hand slightly turned he looked down and noticed that the trackpad/keyboard had a small bit of liquid on it. Most of that was a complete waste of time, just get to the point, you spilled coke on your keyboard, that's all we need to know.
And the ranting and venting posts, just another form of therapy so they can have someone to talk to. Yeah, SOME posts are useful and insightful but most of it is just entertainment for people and another way of social networking. Why do you think MR has a Marketplace here, it's for networking with people so you can sell your stuff.
People use MR as social networking source just like Facebook, Twitter and Ping.