> Emacs buffers are not the reason why functions like forward-paragraph exists.

A buffer is essentially a tuple

    (contents, point, mark, definition of a "paragraph", ...)

So the article is correct - without buffers 0-ary (or implicitly 1-ary, since all evaluation is in the context of a buffer) functions like `forward-paragraph` could not exist. And without a wide library of such functions, the correspondence between normal editing commands and idiomatic Emacs Lisp wouldn't exist, and most benefits of Emacs would be lost.