You have misconstrued Richard's post. He went on to say that what is
useful for newcomers isn't necessarily what they expect or "want".
There's thus no indication there that he would support the rest of your
argument.
This is exactly how I understood Richard, and I think delete-selection-mode
is useful for newcomers regardless of whether this is what they expect.
The answer is to ask them why they want this. C-w is easy to type, as is
<delete>.
<delete> is not the same as C-w. <delete> doesn't clobber the kill ring
with unnecessary text. This is an important distinction. How come
a powerful editor has no key to delete the selected region without
saving it in the clipboard.
Emacs isn't about taking things for granted. It's about efficiency,
about minimising keystrokes, about not getting in the users' way. How
about improving the documentation/menu-settings/whatever so that these
beginners find what they're looking for?
I agree that it's about efficiency, and delete-selection-mode minimizes
keystrokes thus it makes faster editing.