I think it’s actually pretty silly. The same people demanding you no-hello them (that is, try to enforce a social solution on everyone else to solve something t

I think it’s actually pretty silly. The same people demanding you no-hello them (that is, try to enforce a social solution on everyone else to solve something they can easily solve technically) will also tell you to e.g. use an as blocker, or go on about Postel’s law. If a random slack message is going to ruin your concentration, that’s a you problem. Fix it on your end. I agree, it doesn’t especially bother me. But if I don’t want notifications, I mute them. I don’t demand other people accommodate my inability to manage my own attention.