> Everytime I have a serious conversation about the productivity gains or losses of Slack though, it is pretty clear to me that it is more disruptive than helpful.

This past year at Inbox Awesome, one of Slack's team leads asked the audience how many there used Slack. Of the 300 or so people there, around 75% raised their hands. Next he asked for a show of hands on how many people felt that Slack made them more productive. Not a single person raised their hand. It's on video at around 17:30 here:

https://livestream.com/accounts/9197973/events/7910977/video...