Emacs developers viewed it as yanking out of the buffer into the document. Vim viewed it as yanking out of the document into the buffer. It's poor terminology either way, as yanking to me implies moving rather than copying as in both applications
Maybe Emacs yanks from a clipboard (into a buffer), while vim yanks from a buffer into a register (buffer)?
Oh oh. Someone had a too harmonic day and wants to add some spice to it.