> I don't want anyone who's job requires deep, introspective thought on big problems to be constanly distracted by a flashing toast that's probably a non-time sensitive, low-effort inquiry or worse.
Who says he needs to? Your company should have communication policies. They should decide which channels/rooms your junior should join. He's a junior, it is likely no one will urgently need an answer from him for some time, so his settings can reflect that. He does not even need a visible/audible notification for that @-message, he can answer when he feels like it.
Also, your last paragraph make it sound like the people in those roles cannot handle their job responsibilities AND a couple of disturbances.
Yes, I have also heard that repeated ad nauseam. I think it is highly debatable and individual.
I also think a lot of people overestimate how "deep" their own work is compared to others. E.g. a lot of programming is just tedious busywork and scaffolding, yet every programmer here seems to think a slight interruption is a destructive event. Maybe the problem is with you, not others. Maybe you are not a good match for working on a team.
At many companies, plenty of programmers and engineers do complex, meaningful work in a crowded, very busy setting, with lots of talking over each other's heads.
Have you seen how SpaceX or Tesla engineers work?
What some people call deep work others do with their hands tied and constant "interruption".
The vast majority of SpaceX and Tesla work is pure logistics/operations (and everyone I know at either company hates it). You think all those people are doing physics or engineering?
Who says he needs to? Your company should have communication policies. They should decide which channels/rooms your junior should join. He's a junior, it is likely no one will urgently need an answer from him for some time, so his settings can reflect that. He does not even need a visible/audible notification for that @-message, he can answer when he feels like it.
Also, your last paragraph make it sound like the people in those roles cannot handle their job responsibilities AND a couple of disturbances.