In the early days of the Internet, it became customary to refer to Web sites as “pages" though they might in fact consist of many different pages.
The Jane Austen Page, for instance, incorporates entire books, and is organized into a very large number of distinct Web pages. This nomenclature is illogical, but too well established to be called erroneous.
However, it is not wise to write someone who has created a large and complex site and call it a “page."
Not everyone appreciates having their work diminished in this way.