You can view several talks I’ve given on this to understand the differences.
TL;DR:
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systems of fact, data, and science can benefit from downvotes, because statements can be scientifically proven to a reasonable degree.
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systems of opinion do not benefit from downvotes and are in fact materially and seriously harmed by them, because nobody can prove an opinion. Empathy is the order of the day in opinion systems.
On top of that be very aware that Q&A is not discussion, in fact Q&A are discussion are rather opposites. One is a classroom, the other is a restaurant.