I like to use these shortcuts as the perfect example to show that it is perfectly fine for sites to offer different, alternative, functionality based on what the platform and input method can offer:
- Got touch? Great, you can now swipe and pinch-zoom on things.
- Got a keyboard? Great, you can focus elements by tabbing into them.
- Got a pointer device? Great, things can now happen on hover.
- Using a keyboard? Great, you can use handy shortcuts.
A practical example here is a modal dialog that is getting shown: depending on which platform and input mechanism combo you are using, you can close it by flinging it away, hitting the ESC key, doing a back swipe, tapping the backdrop, or by activating the close button.
This is an interesting point about input methods and devices, but I'm still not entirely convinced that this shows much more than the idea that users should have multiple ways to accomplish the same thing. I'm less comfortable with the idea that some users with some devices simply cannot reach the same functions as some users with some other devices, even if using what they'd consider to be a full featured, up to date browser.