No, a meeting or a phone call is synchronous. You can't put a meeting down for 10 minutes, do something, and pick it up later. There is no requirement to answer chat messages immediately unless your organization has ridiculous expectations.
Chat is asynchronous like email, but facilitates faster exchange than email.
With threaded conversations you can keep topics of discussions from getting interlaced. You have to keep reminding people to reply in a thread and have to remind people that slacks value is it is asynchronous. And you have to go back and read the new messages when you do check in. It is swimming against the stream but not impossible.