@evan re: "but you're replying to something that could be private"-- yes, i could be. i could be replying to anything or nothing at all. replying to a cnn article, replying to an overheard statement, replying to the weather, replying to a concept.
one example i think about in this regard is how the Linked Data Notifications spec is technically a response to the Social Web WG charter, because that's what prompted its existence: https://www.w3.org/TR/ldn/
if alice lets you see it, cool! if not...