Why cant i just echo the html elements instead of using multiple <?php?> ??

I haven't done this course, but have been using PHP for years. Basic PHP where you are including HTML inline can get quite messy with multiple blocks of code as I guess you are using.

If you have this (for example)

<?php
 $arr = array( "key1" => "val1"
                      "key2" => "val2"
                      "key2" => "val2");
  foreach($arr as $k => $v)
    echo "<li class=\"$k\">$v</li>";
  //Output would be <li class="key1">val1</li> etc
?>
</ul>

If you were writing a fully fledged web app mixing your logic with your controllers and views would get extremely messy! Now you could start including or requiring various templates/files to tidy code up (I would believe that TH go over that in the e-commerce application).

I would suggest at some point using a template engine such as Smarty, or use an MVC framework of which there are many out there.

I think this course was an introduccion to php and creating a web app. Remember that not all members in treehouse are as experienced as you. The course is a starting point for most users. Just my 2cents