I think that's partly because so many people yearn for more human connection, which in covid times is often expressed as unnecessary Slack conversations. Also, because humans are naturally wired to be drawn toward whatever is most recent; until a few hundred years ago, if an event happened nearby you, that was always the most important thing to which attention should be directed. Finally, I don't think that "avoiding distraction" is even a goal for many people, especially if they're meh about their job or they feel watching current social trends are more important/interesting than their job.
I doubt there is a generalizable solution for these "perils of autonomy." But if eventually we move away from the synchronous messaging that pervades modern office culture, that would be a step in the right direction. Slack needs a mode that debounces messages so they're delivered en masse once per hour unless a box is checked that the message is urgent.
In the future, when more people work as independent contractors, that ought to help too. This isn't a problem that a manager will step in and fix by imposing a new policy, as the story seems to imply.