Matt didn't "make" WordPress. He started the project, which was based on another piece of software, with his friend Mike and now thousands of people have contributed to it in one way or another.
I actually doubt there's much left of Matt's own code besides some of the crap that should be removed, such as hello.php.
I actually doubt there's much left of Matt's own code besides some of the crap that should be removed, such as hello.php.