It's a higher level issue, declarative vs. programmatic environment control. It isn't that sysadmins don't understand programming, functional programming, etc.--everyone is devops these days. It's that in the world of system administration we've gone through many waves and trends with significant backlash against complete programmatic definition of environments.

In the old days you'd exec a pile of shell scripts to go out and put your servers into the state you wanted. It was brittle, painful to understand, etc. Then things evolved into declarative definition of environments with tools like ansible. Now you just define the state of the world you want and ansible or other tools do the work to get the world into that state. This has evolved even further into declarative definition of entire distributed systems with kubernetes--you write out a pile of YAML that defines the state you want and kubetl and k8s controllers take care of making it happen.

So there are definitely people that understand the value of functional programming, but don't want it to define their environments. I don't want to have to grok someone's 'clever' solutions to figure out that ultimately they just want package x, y, z and software foo installed. I just want to list what I want and let the tooling make it happen.