[rbanffy]

> building for reliability has largely died out.

A real shame, but offloading reliability to software engineers makes the hardware cheaper, something IBM mainframes aren't known for.

> doubt many people today are running workloads which "require" a mainframe...

It seems to me mainframes are built with profoundly different requirements than the ordinary hyperscaler server, with a lot more connectivity and specialized IO processors than CPU power. The CPUs are really fast, but it's the IO capacity that really set them apart from the top-of-the-line Dell or HPE.

If IBM really wanted to make the case for companies to host their Linux workloads on LinuxONE hardware, they'd make Linux on s390x significantly cheaper than x86 on their own cloud. I am sure they could, but they don't seem willing to do so.