Sometimes people bring you news or a fact - nothing you can agree or disagree with, it's just a fact. If you like what you hear you can click love, but if the news depresses you, there is no way to express it other than to post a message with a face. "Helpful" covers it - but it's neutral so it doesn't indicate whether you found the information cheering or depressing. Now I wouldn't particularly advocate the button to be called Hate, in case people used it ambigiously. So how about "Happy" and "Unhappy" buttons?
Later: Ignore the disagree/s they're from people who have been indoctrinated by SimGuruDrake to fear any negative button.
"You can do refraction by raymarching through the depth buffer" (c. Reddeyfish 2017)