Ubuntu is nowhere near the only major distro. Maybe on the desktop, but most likely not on the server.
Edit: Also there are a lot of stories of "this old system that is central to our operation that nobody except that one guy 10 years ago knew how to set up" in companies.
I understand that Ubuntu may not be the /most/ popular distro. (tho everyone I know who runs Linux in AWS/GCE/Azure seems to run Ubuntu except me, I'm on Amazon Linux 2)
But the person I replied to said 'all' which is incorrect. If he said 'most' or something I wouldn't have replied :)
Edit: Also there are a lot of stories of "this old system that is central to our operation that nobody except that one guy 10 years ago knew how to set up" in companies.