It was definitely easy to jump from learning HTML to learning that I can run code on the backend and render the output by just adding a tag like this:

    <?php
      $data_from_backend = [whatever I need to do on backend];
      echo $data_from_backend;
    ?>

Right there inside the same document, rather than learning about Node, APIs, a templating engine, etc. It kind of just worked and was very simple. Of course, for professional apps this caused a ton of problems and now using PHP that way is seen as something from the dark ages.