Ask HN: Random FB Questions That Harvest Info?

On your Facebook feed, you'll nowadays find questions that seem phrased in that dopamine-trigger kind of way to prompt a responsive comment, and you'll usually find a few people you know who have commented among the "6.8M comments", thus placing it in YOUR feed.

I remember seeing an explanation as to why these exist - that the question-askers can harvest sort of useful information from the commenters. Can anyone explain? Or are there some good articles/explainers on this I can read and then link to?

(Also, anyone from Meta here who might want to consider the problem?)