There was a huge initiative at CERN to move to non-MS products.

It was great actually: suddenly we were leaving behind a bunch of bloated MS cruft and working with nice stuff. As someone working at CERN I was really inspired, not just by the support for open source but by how well it all worked.

Then next thing I knew we were doubling down on MS stuff. I don't know what happened. It was sad though, and the user experience did not improve in the end.

I'm not close enough to CERN-IT to know the details. But for what it's worth, no one I knew in IT could think of a good reason for going back.