I don’t know if I’ve ever heard of anyone who just uses Teams, but I’m sure there are some. I’ve heard a lot of people only use Slack, and I’ve heard from some Meta people that they have their own internal chat, not sure what it is.

I’m at one of the mostly-email companies, though culture seems to be shifting to chat for more things, depending on who you work with.

I think for HR people, it probably wouldn’t work well for anything official. And if you aren’t at a company that already has chat culture (and the tools for it), then it’s a non-starter. But I bet that at the right company, even in HR, you could move a lot of non-critical email into chat.