Yeah, see, Mac keyboard equivalents actually predate most other OSes. So no, they're not going to change to accomodate the newcomers. option- shift- and command- arrows have been there since the 80s. Not going to change because Windows decided to do it differently.

As for discoverability, it is worse today, but historically there were no keyboard equivalents that were not in the menus (by Apple's UI guidelines), so discoverability was better on the Mac.