Maintaining inherited environments is also much more painful than ones you get to design from the ground up. I work with varied environments, and one with ~250 RHEL / CentOS machines has approximately the same level of maintenance burden as another with a dozen or so Ubuntus because the first environment has had configuration management from the beginning and the second is a complete mess that I've slowly tried to reverse-engineer and clean up.

When your change management works, maintaining a dozen servers isn't all that different from maintaining a thousand or more; and the need for change management and automation doesn't really go anywhere even when you don't self-host things.