Tom McFarlin wants to correct those that claim WordPress is a framework.
And although we can build our own applications on WordPress, that doesn’t mean WordPress is a framework. Because, unlike the rest of the frameworks that are listed, WordPress is a complete, fully-functional application upon installation.
In the end, he calls it a “foundation”. Which is perhaps a subtle, but important distinction.
Also check out Tom's new Start Here course, either for yourself to learn, or to recommend to aspiring WordPress professionals.