With async communication, the expectation is that they can generally take as long as they need. You put your message and maybe they'll get back to you then or i

With async communication, the expectation is that they can generally take as long as they need. You put your message and maybe they'll get back to you then or in 5 minutes or in an hour, etc, but they have all the information to orient themselves on their own time. If you just go "hello" and have this synchronous chat, then there isn't time to orient yourself, because the expectation is to respond as if you're in a face-to-face convo.