Distraction is not enforced. Learning to control your attention and how to help yourself do it is crucial whatever you do in whatever time and in whatever technological context or otherwise. It is the most long term valuable resource you have.
I think we start to recognize this at larger scale.
Slack easily saves a ton of time solving complex problems that require interaction and expertise of a lot of people, often unpredictable number of them for each problem. They can answer with delay, in a good culture this is totally accepted and people still can independently move forward or switch tasks if necessary, same as with slower communication tools. You are not forced to answer with any particular lag, however slack makes it possible when needed to reduce it to zero.
Sometimes you are unsure if you need help or you can do smthing on your own. I certainly know that a lot of times eventually I had no chance whatsoever, because knowledge requires was too specialized, this is not always clear. Reducing barriers to communication in those cases is crucial and I don't see Slack being in the way here, only helpful.
The goal of organizing Slack is such that you pay right amount of attention to right parts of communication for you. You can do this if you really spend (hmm) attention trying to figure out what that is and how to tune your tools to achieve that.