I’ve had Mac since Snow Leopard, and recently Fedora on my desktop. In macOS command+arrow jumps to the begging or end of the line and option+arrow jumps words. If you hold down shift in addition, the words get selected. It has “always” been like this consistently!
I definitely used Snow Leopard, it was released in 2009.
This was a problem in Snow Leopard and probably the two next releases as well: I always upgraded as soon as possible.
I used Mac OS X from 2009 to 2012.
It was sold as consistent and keyboard friendly back then.
However: Describing a desktop interface where selecting a single word using the keyboard needs a different keystroke in different apps, that is - rich.
Maybe this is fixed now but back then even official applications had different ways to select a word using the keyboard: in one it was cmd+shift+arrowkey in the next it was ctrl-shift-arrowkey or even fn-shift-arrowkey.
Especially infuriating because one of the most used ones in other applications meant "navigate back" in Safari.
Meanwhile in Windows and Linux ctrl+arrowkey always moves one word and ctrl+shift+arrowkey almost always (hi Excel!) selects a full word.
Maybe it is fixed now. But I'll never let a Mac user lecture me about consistency again.