RE: C-x 2 and C-x 3

[Drew Adams]

> Copying is an implementation detail.

No, it has nothing to do with implementation.  It is a user-level operation.
Just like using `C' in Dired is a user-level copy operation.

> The purpose of the command is to make a new window.

Almost, but not quite.  The purpose of the command, what the command does, is to
make a new window...that is a copy of the selected window: same buffer.

The command copies the selected window.  It does _not_ just make a new window.
It makes a new window with the same buffer (and same window-point value etc.).
And that's the point.