If someone wants to talk in person or via voice instead, my heart always sinks a little, because it means I have to drop whatever I was doing and give the conversation my full attention instead. Once we're done, I have to try to remember what I was thinking about before the distraction happened, get myself back up to speed...
This doesn't come up so frequently anymore, but it was very noticeable when I used to work remote. Some coworkers were happy with chat, and it was easy to communicate with them; with others, it'd be like twenty seconds of productive conversation, then "can we please just have a call about this" and, oh god, that's it for getting anything done for the next 40 minutes.
I find the same to be true on (small) Slack (or similar) channels. Which is funny given that Slack being synchronous is one of the two main points of the link.
Chats are much less interrupting. When someone walks in, you have to look at them (it's rude to keep typing and look at your screen), your brain starts to assess who it is and their mood and pulls into an appropriate facial expression, and you have to start listening because your audio buffer is much more volatile than your chat client's message log. Even if you're just finishing the "hope to hear from you soon" of an email, you typically have to acknowledge someone's presence and already detect who it is (someone two levels above your paygrade, you'd not want to keep waiting, while you would let a peer wait for that email to get sent out). I don't know how much of that subconscious activity really interrupts flow, but I notice it's annoying.
For chat, group messages don't trigger notifications and they just get looked at when I have a second. If someone needs me specifically, they'll mention me or send a private message. In those cases, I will notice the notification but will (depending on how concentrated I am) either not process it beyond "there's something" or not beyond judging whether it's urgent (based on the first five words, or whatever makes it into the notification). I catch myself thinking "wait, someone sent me something, I totally forgot" and it turns out there are no unread chats. What must have happened is that I alt-tabbed back and forth to make the unread-message counter go away (and give them the double tickmark to indicate I saw it) because what they sent did not need further processing (something like a final "okay"). That did not interrupt flow.
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On top of that, what others have said: external people (at clients', at home, whatever) can follow chats along; you can do stuff in between messages; you can pick your nose during conversations; and you can have an 80 second meeting between five people.
I think an uninterrupted private office and "instant" messaging are not mutually exclusive things.
Personally I've noticed people tend to take a longer time saying something in chat than they would in person. And if I have to wait for a reply I'll probably start doing something else, potentially making the chat conversation go even slower.
I have little experience with group chats, in my limited exposure to them they tended to be more focussed on fun than productivity.
I also seem to be one of the few people that can quickly context switch between a conversation and actual work.
> But personally I prefer a little personal interaction over a long chat.
Although it's hard to schedule an 80 second meeting between five people, but a quick set of questions and answers might only take that long.