Mainframes are the polar opposite of commodity hardware. Those pizza boxes are commodity because they're plentifully available, and you can mix-and-match if nee

Mainframes are the polar opposite of commodity hardware. Those pizza boxes are commodity because they're plentifully available, and you can mix-and-match if needed, there's nothing cheaper for you to run your VMs on. Running them on a mainframe would put IBM as a middle man between you and your business. Also, mainframes/midranges are all about stability, security, and robustness, not performance. For example, IBM i (the OS, not the machine) has a hardware dependent layer, and a hardware-independent one. This allows for drastic hardware changes without affecting the high-level applications. A monolith would be arguably more efficient, but it matters more that the hardware-independent layer stays rock-solid. https://en.wikipedia.org/wiki/IBM_i#Architecture https://en.wikipedia.org/wiki/IBM_i#Architecture