What are the drawbacks of concatenating HTML fragments using echo and print statements in PHP for building navigation menus?

Concatenating HTML fragments using echo and print statements for building navigation menus can lead to messy and hard-to-maintain code. It can also make it difficult to separate the HTML structure from the PHP logic, resulting in a lack of readability and scalability. To solve this issue, it is recommended to use a templating engine like PHP's built-in `include` function or a third-party library like Twig to separate the HTML markup from the PHP code.

<?php
// Example of using PHP's include function to separate HTML markup from PHP logic

// Navigation menu HTML fragment
$navMenu = '<ul>
                <li><a href="#">Home</a></li>
                <li><a href="#">About</a></li>
                <li><a href="#">Services</a></li>
                <li><a href="#">Contact</a></li>
            </ul>';

// Include the navigation menu HTML fragment
include 'navigation_menu.php';
?>