Perhaps having an OS polyculture is a luxury afforded to organisations with lots of time and money to wear the inefficiency cost of doing things 3 or 4 differen

Perhaps having an OS polyculture is a luxury afforded to organisations with lots of time and money to wear the inefficiency cost of doing things 3 or 4 different ways, or who want to intentionally prop up a competitor to ensure there is market competition (it's fabled that IBM bought so much SLES to provide a competitor to Red Hat), and maybe some other reasons. An Ubuntu monoculture at least gives you an easy migration path to Debian.