Actually, a page was found. But not the page sought.
If no page had been found, then the user would see a blank screen.
A logical name would be “the page requested does not exist.” Showing “page not found” is similar to the false statement “This page intentionally blank.”
An explaination:
“404” is the number of a standard error code a browser shows when a link to a page is broken, or missing, and no page is found.
If a page is not found, then the choices are:
1) show the error code only.
2) show a blank page.
3) provide a page that contains an explaination.