According to the Hierarchical Rendering here, content of app/views/layouts/posts.phtml should appear when loading /posts URI (https://localhost/myapp/posts). So I tested the example given in the documentation:
<!-- app/views/layouts/posts.phtml -->
<h2>This is the "posts" controller layout!</h2>
<?php echo $this->getContent(); ?>
and
<!-- app/views/index.phtml -->
<html>
<head>
<title>Example</title>
</head>
<body>
<h1>This is main layout!</h1>
<?php echo $this->getContent(); ?>
</body>
</html>
and it works, so great.
But I am wondering why do we have to use <?php echo $this->getContent(); ?> to make the "hierarchy system" actually work (if one remove it, it does not work anymore), what the point of having an "hardcoded" system if one have to add this code ?
Thank you