Yeah but dude that's 3 different languages, and in fact in PHP, much like CSS, you can miss off the closing delimiter, if it's the last section of code, as it is not needed.
<?php include("sitevariables.php");include("header.php")?>
Will work the same as ~
<?php include("sitevariables.php");include("header.php");?>
If I then want to add something else on and i get an error, I look at it and say o I missed the delimiter.
All you need to do is change it when you add something new. Not that much of a big deal TBH, as you are cutting bytes and thus server strain which is a lot, lot better.
Personally I would disagree with that, as you are shortening your code, this reducing bandwidth, sever strain and increasing page preformance be it slight. It's extra code that doesn't need to be there so can safely be removed.