Because to me, they seem like de facto "Agree and “Disagree” buttons, whether or not it was the intent.
That is, are upvotes “yays” and downvotes “boos”?
I still upvote posts in news communities informing me of terrible things, so upvote isn’t necessarily a yay. Downvote might be boo, though
hm, I do think what I meant by “yay” is some kind of supportive or positive emotional response, which is still happening when you are upvoting terrible news for being informative, i.e. what you are responding to with “yay” is being informed and wishing others to be informed, not the content of the news itself.
(For context I’m drawing on the metaethical theory of emotivism here as a framework.)