Personally I find that they can, but they don't have to. I can put off Slack/email until I hit a stopping point, or I can wedge it into the middle of a long-run

Personally I find that they can, but they don't have to. I can put off Slack/email until I hit a stopping point, or I can wedge it into the middle of a long-running process (start a build/test-cycle/deployment, then go answer Slack). At the very least I can finish the chunk of code/whatever I was working on. Phone calls and in-person talking are a hard interrupt, drop all my context on the floor and get nothing else done.