When selecting copy/paste from the right-click menu, why does Google Docs pop up a dialog to say "Copying and Pasting in Google Docs", with the message "These actions are unavailable via the Edit menu, but you can still use Ctrl-C or Ctrl-V" etc when it could just do the operation direct from the menu?
Copy and Paste is in the menu...

...but selecting it says you can't do it, use Ctrl-C etc

What was the design thinking behind this? I can't understand why one can't just do the operation, after all:
- It provides the menu options: copy and paste
- when you select these, it knows what they are to tell you
- it can do the copy and paste but via Ctrl-C, Ctrl-V etc.
- Surely they can link the Google Docs code that handles the menu selection with the code that actually does the operation
Was it a patent issue? A security issue? Or some kind of user interface conflict that made this extra step mandatory?