You can see who upvoted and downvoted a post by viewing it in friendica.
submitted
irelephant 🍭
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Upvotes seem to just federate as likes and dislikes.
Interesting idea, but how do you decide on what the universally-agreed on reactions are? Have too many and they may as well just be comments!
A fair point that I admittedly don't know how to solve. The closest I've got to a "functional" idea is to focus on splitting the two (I think? maybe three) things that an "upvote" is interpreted as, and supplementing with also the opposite / counter message:
Pretty much everything else can be a comment, as you say, but the purpose and reception of a message should also be as streamlined to communicate as possible.