I’ve never worked with major enterprise or government systems where there’s aging mainframes — the type that get parodied for running COBOL. So, I’m completely ignorant, although fascinated. Are they power hogs? Are they wildly cheap to run? Are they even run as they were back in the day?
Part of that is the racket that is software licensing for mainframes. Many vendors like CA7 charge based on the machines computational capacity. You can introduce soft limits or send usage reports, but not all vendors accept that to lower your price. Super expensive software costs, at least back when I worked on zOS.