Of course you can assign moral blame however you please, but the relevant "policy" question (in both the gun case and the slack case) is empirical.You absolutely can but if there's something about my post that insinuates any sort of 'moral' blame that a comparison to the "Guns don't kill people" trope (there's probably a better word for this) is warranted, then I've massively failed to express my intent clearly. Allow me to unpack this a bit for clarity.
The logical framework for "Slack doesn't disrupt your productivity, you allow your productivity to be disrupted" is certainly there, but that's about where the comparison begins and ends to the "Guns don't kill people" argument.
What I instead mean is tools like Slack and other real-time persistent chat apps definitely exacerbate FOMO and the need to reply, respond or react in someway to a notification. Their express function is to notify, to that end they're doing what we effectively ask them to do by using them in our workplaces. Note: I'm speaking rather broadly here, I'm quite aware you very rarely have a choice in the matter when joining a new company what chat service you're stuck with using.
But as I mentioned in another comment, they have this capacity about as much as a hammer has the capacity to injure a user trying to drive nails and hang a picture.
My curiosity of how we effectively 'blame' (pretend I'm speaking with a velvet glove here when I say blame I mean it as positively and delicately as possible) Slack for breaking our concentration is with the hammer analogy in mind. Certainly it has the capacity to disrupt but just like one would probably hold and use a hammer delicately enough to avoid harming themselves but deliberately enough to drive a nail, our comms stacks can easily be wielded just as well.
(That was a bunch of words up there above, but let me raise my hand right now and admit that I am absolutely guilty of checking every notification I see come in and breaking my own flow, it's why I even hold this position).