This is probably a bit deep, but i cant really find anything online where there's discussion about it so thought it was worth a try here!
It's something I notice in comments, particularly on youtube and large forums like reddit. I've noticed it for years but hadn't really tried to articulate it.
So, most upvoted or popular comments, which tend to rise to the top (become most visible) tend to be similar in style. For example, beneath an anatomy (science related) video I watched last night the most popular comments were 'personal', as opposed to intellectual (as in referring to the actual video content).
Such as "I watched this video 3 hours before my grandma passed away". This comment received over 2k likes 
Or "My dad once had a fall and broke his leg, us kids were all sent to stay with our uncle ...." etc etc.
Another example was a Panorama special about alcohol regulation in the UK. Most all of the comments involved very personal stories rather than any discussion about the actual regulation or greater topic.
People rarely mention or comment on the actual content/subject matter, over all. So I wondered why that is. I suppose it stands out to me because I would prefer to read comments that discuss the content further, especially with educational or creative stuff.
This brought me to the conclusion that the majority (I'm generalising of course) of people online who leave and like comments are attracted to 'human interest' or personal stories rather than discussion about the subject.
This might seem bland on the surface, like no one is interested in getting deeper or considering a subject or idea - but maybe it is something inherent in human nature. Are we, on the whole, drawn to emotional/personal stories than discussing abstract ideas?
You might answer 'both!', but I do notice that it leans towards the former way more often.
I don't have any judgement towards this, but am intrigued. I even wonder if my mind works in a peculiar way, but then again we are all just different. Perhaps people like me tend not to comment as often? I know I don't! I would love to hear if anyone has ever noticed this, and has any thoughts about it.
Sorry this is so long. It was a bit difficult to describe.