You need a web server in order to serve the webpages.
You dont necessarily have to use PHP's FTP functions, since you might be able to do what most people do: upload the PHP scripts via FTP, then the rest of world downloads the scripts via HTTP, after the web server has parsed them using PHP.
Conversely, you could have a PHP script that connects to the files via FTP too, and then dynamically displays them.
In this case, you'll have to use PHP's FTP functions.
But the PHP script still needs a web server in order for the dynamic webpages to be served to the user.