I disagree, it was a common pattern to have a single .php file for each page, independent from each other, which would receive input params (GET, POST and COOKIE), sometimes connect to the database, and do all the processing inline, outputting the result. The whole file was essentially an implicit function. The appearance of frameworks with a single entrypoint and which load models and controllers and such is fairly recent in the PHP world. When I started writing websites, already in the 2000s, this was how I first learned.