i'm also confused at why humans, who are social animals, might enjoy knowing that what they say is enjoyed by others. and, by receiving feedback from users they respect, they can adjust their behavior and engage in a more pro-social and cohesive way in a community they want to engage in
i am further bewildered by the idea that someone might enjoy seeing a reaction to an old post in a thread, both for personal gratification and the notice that a thread they were interested enough to post in but not interested enough to watch might have some minor yet informative update
of course, i also happen to be an alien who has come here to observe your species' strange behavior from afar as a research. are you another one of us? don't lie. you'll know the special handshake if you are