CMS EDIT was designed when the 3277 was the standard terminal. Those things had a SYSTEM AVALIABLE indicator on the center of the right side of the screen, outside the text area. That was the current-libe marker! When the 3278 came out, all the indicators moved to before the text area, but by then, everyone had moved to EDGAR or XEDIT.
The extreme experience requirements are generally exaggerations. They only happen to exist because there are people who really do have those many years in this field. But I've gotten jobs (I'm a systems programmer, many hats style, z/OS and Linux and C and JCL and Shell and REXX etc) and I've gotten jobs before from these sorts of excessive experience postings before despite me being fairly new to the field (just reaching senior level, about 5 years experience in my subdiscipline, which is systems programming, as opposed to applications programming or security, two other primary specializations for people with CS degrees, there is also operations and IT work available for mainframes but probably the pay rate would be of no interest to somebody on HackerNews).
And the Community Edition even has a handy DIR command for you.
This document has a lot of things left to add - the machines can really be a lot more interesting. So far, I haven't figured out how to connect my real printer over the network, the other machine with shared disks but no OS, and even creating a new VM for our user. I also know there are a lot of other interesting things on the base CE image that can be super cool to show a newcomer.