Until Github came along, "Creating a copy of software for your own personal use" had never been widely-accepted definition of the word "fork" in the context of software development. Forking a project has always involved independent publication and maintenance of said project.
The typical way of copying a project for your own personal use on GitHub involves publishing that copy on GitHub. So, it is a real fork—maybe not a well maintained one, or one that the author is particularly excited about, though!
Until Github came along, "Creating a copy of software for your own personal use" had never been widely-accepted definition of the word "fork" in the context of software development. Forking a project has always involved independent publication and maintenance of said project.