I talk a lot when I game and I'm familiar with all the different voice chat software (except Discord)
Discord is what we actually use, because you can paste clipboard data (particularly pictures) easily and have historical views everyone can see and shared text chats with seperate voice channels. Mumble was never really an option because it loses chat history (unlike Teamspeak, however Teamspeak won't synchronise chat buffers with everyone, so you won't see historical things that happened if you weren't there).
How the hell do you concentrate on your work when a couple other people are literally yammering on in your ears? Do you just not talk that much? Do you have separate channels with only two or three other people in them? Do people just not work at all when there's a necessary conversation happening?
If it's off topic to my work and disturbing me, I move to another "virtual office" voice channel (typically those that are working on the same project at that point in time will be in the same "virtual office" voice channel together).
I suspect another part of it, is our work culture is based on the idea of flexibility, so when we're working, we're working hard, when we don't have anything that needs to be done, we can leave early (but contactable by mobile if there is anything) etc. So, this leads mostly to a culture of people that are usually focused on getting the job done well and focused during working hours, because we're not forced to work all "working hours" if there isn't a need to. However, it also means that there are rare times when you are expected to work extra long hours (and nobody seems to complain/have issue when it happens, but that might be because we're mostly veterans of large consultancies that liked to make people do 100 hour work weeks regularly) during crunch time (but that happens really rarely). I suspect that, that alone makes people less chatty and more work focused maybe?