Why should I use bitwise/bitmask in PHP?

I am working on a user-role / permission system in PHP for a script.

Below is a code using a bitmask method for permissions that I found on phpbuilder.com.

Below that part is a much simpler version w3hich could do basicly the same thing without the bit part.

Many people have recommended using bit operators and such for settings and other things in PHP, I have never understood why though. In the code below is there ANY benefit from using the first code instead of the second?

<?php
/**
 * Correct the variables stored in array.
 * @param    integer    $mask Integer of the bit
 * @return    array
 */
function bitMask($mask = 0) {
    $return = array();
    while ($mask > 0) {
        for($i = 0, $n = 0; $i <= $mask; $i = 1 * pow(2, $n), $n++) {
            $end = $i;
        }
        $return[] = $end;
        $mask = $mask - $end;
    }
    sort($return);
    return $return;
}


define('PERMISSION_DENIED', 0);
define('PERMISSION_READ', 1);
define('PERMISSION_ADD',  2);
define('PERMISSION_UPDATE', 4);
define('PERMISSION_DELETE', 8);

//run function
// this value would be pulled from a user's setting mysql table
$_ARR_permission = bitMask('5');

if(in_array(PERMISSION_READ, $_ARR_permission)) {
    echo 'Access granted.';
}else {
    echo 'Access denied.';
}
?>

non-bit version

<?PHP
/*
   NON bitwise method
*/

// this value would be pulled from a user's setting mysql table
$user_permission_level = 4;

if($user_permission_level === 4) {
    echo 'Access granted.';
}else {
    echo 'Access denied.';
}

?>