Good question. I looked a very little for the code that does the logic but didn’t find it.
Using the topic I used to answer your post in the other topic
It says there is a total of 116 Likes in the topic. If my math is correct, all of the posts in the Summary have Likes, but only add up to 78
So some posts that received Likes did get collapsed.
It seems that Frequent poster may be in play, and possibly OP.
Some of the Collapsed posts had from 1 to 4 Likes.
Some were shorter replies, some not so short.
Some were “infrequent” posters, some were not.
Some had cross-reference links, some did not.
And I’m guessing there may be some kind of “keyword” matching involved.
I can’t grasp the logic and would need to see the code involved.