I have a question about the seemingly increasing requirement that job applicants be familiar with the AS400 computing environment.

Now I understand if one is an IT person, but why is this showing up in accounting and administrative jobs? What is so different about AS400 system applications that is dictating the requirement? I watched a tutorial on Lotus Notes and Domino, which are probably the two main apps and am not seeing what's so difficult. Or is the problem not in the apps but rather navigating around the system for the common user? Or are they using this requirement as a weeder requirement for those who have, say, large business vs small business experience?

Will someone please fill me in?