>If you use some include() in php, you can avoid long php/html pages...
In my experience, you just get long PHP pages including other long PHP pages, globals defined in one and used in others, included files that contain nothing but HTML, and other madness.
You can certainly GET SHIT DONE in PHP with a bit more coherence. Composer, with its autoloader and a router (probably nikic/fastroute) won't get in your way, your code will be more organized, modular, and lightweight, dependencies can be managed, etc.