There's very little productive going on in those group chats. Far more socializing than anything else. Memes in particular abound. And the interruptions are constant, driving my productivity to a fraction of what it should be otherwise.
Really, email was great, and 10 years of freelancing taught me to be a very good communicator on email (maybe even over communicating).
Now all that is ruined, and I'm trying (unsuccessfully so far) to bootstrap a software company so I'll no longer have to spend my days chatting about trivial matters on Slack when I have work to do.