Maybe I don't use FB enough but I hadn't heard of this "f" thing (beyond 'F' being a Call of Duty meme). I imagine it's an unexpected usecase for Facebook and o

Maybe I don't use FB enough but I hadn't heard of this "f" thing (beyond 'F' being a Call of Duty meme). I imagine it's an unexpected usecase for Facebook and one that would better be served by making a prominent "subscribe to notification" feature, rather than coming up with a machine learning solution. What if the parent comment is a quiz type question for which there are answers A through F? Admittedly it's an edge case but it's an example of how diverse the strange ways people use FB for commenting and discussing.