I think you are underestimating the scale of what a Z system can run... You might not have a use but every fortune 500 and banking institution in the world does - and they need it to work, 5 9's isn't good enough.
> IBM Hursley laboratory director Rob Lamb says: “There are 6,900 tweets, 30,000 Facebook likes and 60,000 Google searches per second." The mainframe CICS runs 1.1m transactions per second, which equates to 10bn per day [0]
> IBM Hursley laboratory director Rob Lamb says: “There are 6,900 tweets, 30,000 Facebook likes and 60,000 Google searches per second." The mainframe CICS runs 1.1m transactions per second, which equates to 10bn per day [0]
[0] http://www.computerweekly.com/feature/Can-the-mainframe-rema...