Does it matter? Microsoft won by default with Teams because it actually turns out no one cares about chat or even has a choice in it: employees use whatever the company picks.
If you're going to say "other than the US" then you've got to say at a minimum "other than the US and China", but really "other than the US and China and Japan and Korea and Taiwan and Thailand and Russia and most of Central Asia".
Only mentioning the US is wildly americentric even by HN standards.
