Why is there no Paste function in iMessage?

The Copy ( Command + c ) and Paste ( Command + v ) are a System Wide Function and not excluded from Messages.

The copy and paste is messages does exist.

Working in Full Screen Mode will hide the Edit Menu but the keyboard command still function.

It worked for me (⌘+V).

▷ Messages User Guide. 

Ratz227 wrote:

Copy and Paste seems to work fine. I was used to Mail, where there is an 'Attachment' button. And never understood why the 'Attachment' was left out of iMessage. I use 'Command-Shift-Control-4 to make selections, and it pastes in just fine. Thank everyone for their input.

AFAIK that feature was never included in Apple Message so could not have been left out off if was never there in the first place.

At least - since joining the Apple Eco-System in OS X Tiger version 10.4 on a Motorola PPC up to and including Monterey macOS 12.1

So to be clear , Copy And Paste does function as expected and as such answers the original Question " Why is there no Paste function in iMessage? " ?