Function key shortcuts have never been a significant Mac paradigm, and for good reason. Apple certainly would never put something OS-centric like 'close window' on a function key. They use contextually-relevant letter keys for shortcuts, and have been on a decades-long crusade to destroy the F-keys entirely. They haven't shipped a system with function keys that defaulted to function keys in 15 years; it's third-party software and the odd legacy text-based UI where you find them. The controls these are used for by typical users (volume, music, brightness) are not really things you need to be able to hit without looking, and exactly why I can see this succeeding on the Macbook where it was a frustration on the X1.