Yup, this guy gets it. Slack and other real-time messaging apps should be treated as a phone call or a knock on the door; an intentional interruption for something important enough to warrant a real time conversation.

Everything else should be handled through email, to allow people to consider and tailor their responses, to allow others to be added to the conversation through a CC: of a single focused thread, and to provide a directly searchable historical record of conversations.