It wasn't an absence of a market. Those of us that had to manage OSX Server soon found out the software was marked by several high-profile bugs, technical debt, and a perceived decline in reliability. I migrated a large number of Macs to Ubuntu Server software. The hardware was great.

I fear the quality of macOS is deteriorating today in the same manner than befell OSX Server.

https://www.darkreading.com/cyber-risk/apple-blasts-mac-os-x...

https://en.wikipedia.org/wiki/Year_2038_problem

https://www.letemsvetemapplem.eu/en/2024/10/19/chyby-v-macos...

Not very useful context considering that was before iOS development took off

Mac OS X Server was..

.. macOS but with a utility to install apache/ldap/smtp/carddav and caldav.

very useful for a home server.

absolutely no benefit over Linux for the majority of the workloads it was designed to simplify.

It wouldn't really give you much unfortunately, certainly didn't run noticeably leaner.

(I think at some point "server" just became an .app that was available via the app store).