It's still a script though. If there's a need for a script at all, one may as well do `php index.php > index.html` or use a static site builder as that will give a lot more flexibility.

Simplifying the process of creating static sites and avoiding existing tools has been tried many times and none of the solutions is really satisfying. In the end, most require "just a small script", but which is likely to grow in complexity over time. I guess creating static sites is not that straightforward so it makes sense to use existing tools to keep things simple.