What are the drawbacks of avoiding the use of PHP sessions for form data management?

When avoiding the use of PHP sessions for form data management, one drawback is that it can lead to a less secure and less efficient way of handling user data. Sessions provide a way to store user data securely on the server side, preventing data tampering and unauthorized access. By not utilizing sessions, you may need to resort to less secure methods such as storing data in cookies or hidden form fields, which can be manipulated by users.

<?php
// Start a session
session_start();

// Store form data in session variables
$_SESSION['username'] = $_POST['username'];
$_SESSION['email'] = $_POST['email'];

// Retrieve form data from session variables
$username = $_SESSION['username'];
$email = $_SESSION['email'];

// Clear session data after use
session_unset();
session_destroy();
?>