No offense but it was the US Government. Most of their websites were coded for it, and quite a few of them didn't work properly or reliably in other browsers as a result. This was true up until it was sunsetted and they were forced to update to edge and some of the websites still haven't been properly moved over to chromium. When the pandemic hit and the Armed forces had to setup remote work for thousands of people Microsoft basically built them a fork of Teams. The US Government is kind of running hand in hand with Microsoft on a lot of stuff if you just hazard a cursory look.