To be fair, what do you expect people to talk about?
5-12 comments covers most topics for a given article/meme. Any more than that, and it starts to just become a repeat of what someone else said.
Do you want to read 10 copies of "lol that meme is so me!"
I always thought it was wild that your average thread on Reddit could garner thousands upon thousands of comments, with the vast majority of them being repeats of something someone already said.
Then factor in that those same comments are in the next thread, and the next one. That's not engagement, that's insane!
The comments here are far more sparse, but they still cover all your bases. You still get the interesting info dump from some expert or hyperfocused individual who's done a bunch of reading, you still get a humorous pun or joke, and you still get the "well, actually, this is wrong because..." just, now, it's like 1 of each type instead of a thousand people all trying to crack the same joke in one thread.
Edit: to clarify, I mean 5-12 top level comments