@Felthry Yeah. My guess is, using the (former) menu used Google's clipboard internal to the app, while the keyboard shortcuts use the OS, since those are the standard keys for that. Possibly they're getting rid of the Google clipboard entirely.
For reference, the messages I've seen have been using Google Sheets within an old version of Internet Explorer, on a Windows 7 machine.
@emanate At the very least that would make it not what it looks like, which is "making things harder for people just to force them to learn a thing" (which is not good)