Also, many people seem to want to get a reply to their "Hello" before they type more, so you have to switch over to the chat tab instead of just ignoring the notification.
A cordial greeting before an ask is mostly an empty gesture anyway. If you actually care how someone's day is going, ask in person or via a message with more substance.
I’ll see a “Hi!“ in a notification or followed by _x is typing_ then safely know that I can start slow context-switching out of whatever mode I’m in, start reviewing that block of work for check-in or noting the key takeaways to come back to, and start pre-loading whatever I was talking about with that person last, without the fear of “here’s a big block of text, please respond to it in kind (all right away)”. And more than that, I can also interrupt any incorrect lines of thought or rambling if it’s more rubber-ducking than a request, or turn it into more of a conversation than a message which can read “please do this” and a reply which says “um... let me get back to you”.
I don’t know about you, but a large technical question or “hey can you... X Y Z” generates much more uncertainty than a chat between colleagues, even if the format is only different. Hell, modes of communication are a thing, we’d be as well use each one for its strengths.
About a year or so ago I came up with a solution to this problem: turn off all notifications. I don't revive notifications for emails, chats, texts – anything except phone calls. That's the only thing. I also have a notice in my chat status at work, and wherever else it makes sense: "For urgent matters, please call me at <phone number>."
It's worked wonders. I can choose to respond whenever I choose to check my messages, and for anything truly important people do call. It's happened maybe a half a dozen times over the past year that anyone's actually called, and typically whenever I'm non responsive in chat (because I didn't see it) I'll get an email instead, which generally has more detail in it anyway.
This, along with using mornings to square away most correspondence, has worked wonders for my concentration. My afternoons are now mostly focus time, despite people texting and emailing. I just get back to them later. Maybe tomorrow morning.
For people whose job it is to be notified of things, likely the author the website included, how is this relevant?
Not everybody has the liberty to choose when to check messages or respond to them, especially those who are using a chat system which usually demands an instantaneous response. People collaborating on projects, people working to a deadline, companies which favour Slack or similar systems over email, and in my own example, people on IT helpdesks.
While I'm glad that you've managed to regain control of your routine, I'm not sure I see how it's relevant to the scenarios applicable to those hinted at through the context of the website.
And I do get some blocks of time when I can ignore all interruptions, in which case I just don't even open chat, instead of having it open and disabling notifications.
(My job isn't weird; I'm an SRE on a support rotation. When I'm on support I need to see things urgently; when I'm not I can focus on project work and escalations can take the form of someone finding me and pulling the headphones off my ears if needed.)
More fundamentally, not being around on the medium that most people at your company use in order to focus on project work is a great way to get left behind in terms of being aware of what the business is doing and what it values. People will slowly see you as the person who's great at finishing their own projects but not usefully responsive, and start treating you that way. Including when trying to assign new projects or during performance review season.