This is a great example of why Emacs (and the lisp machine idea in general) is so amazing. Though as a demonstration of the power of emacs it's understated; I thought this was going to require some advice or dynamic rebinding.
I think all this, distraction aware apps, open a new killer feature that can bring healthness to teams. It is obvious that Slack omnipresence can get you mad but they can easily infer that you cannot attend every @channel or @your-name tag. In this case Slack can be a mediator and recommend abusers to slow down or bring specific analytics tools to executives to improve communication structures.
On the particular case of slack, using their irc gateway one can use any irc client, which probably has already some kind of distraction-silencing method. Also, IRC bots are now slack bots. As another emacs' extensibility showoff here's an example for temporarily ignoring users[1].
Unfortunately, slack is adding more and more features every day that do not map easily to IRC.
True. I tried using Erc for slack for a while, but it started getting a bit limited.
To be fair though, as they add more features it gets hard for client-apps to keep up as well.
If your users have avatars in their usernames, makes them go away in the source of slack-user-message.el in slack-message-sender with
I found people with stuff in their statuses made room names distracting, especially with group chats In slack-im.el, in slack-room-display-name, I am not good enough at Elisp to figure out how to make these hooks and I've been a bad open source person at opening an issue on these.