Mainframes have to implement a fifty years old architecture, and I suspect they have vastly smaller engineering teams, since their market is orders of magnitude

Mainframes have to implement a fifty years old architecture, and I suspect they have vastly smaller engineering teams, since their market is orders of magnitude smaller than those of Intel or ARM. Also I seem to remember IBM being seriously hostile towards independent benchmarks. Also, if they were competitive wrt performance, people would be using them. In real life they are rarely found outside of financial institutions.