To each their own. My goal is to set very rigid expectations on when I'm reachable or not. And to enforce with myself what my priorities are. If I'm not at my PC my priority is not reading or writing slack messages.

How is that incompatible with the parent poster's point? You can have an app installed and not open it just fine.

What's the point of having it at all then? For me, there is never an appropriate use for slack + phone. My job will wait for me to be at my desk.

You have the app available in case you need to communicate (outgoing.) It's like a phone you never answer, just like my land line.