Because doing it this way sucks. I used to do it this way a decade ago when I was learning and it was hell to maintain and keep consistent. It's the reason why

Because doing it this way sucks. I used to do it this way a decade ago when I was learning and it was hell to maintain and keep consistent. It's the reason why I learned PHP in the first place (stuff like `include('header.php')` blew my mind!), because I was aware of the problems and went looking for a solution.