Yes that’s the old way of doing things. I mean since many years there is no need to use apache’s sites-enabled. Just in your own words, you tells a lot about different issues concerning the internet side of WordPress
If there’s nothing in the WordPress config and installation making it accessible from the internet, then WordPress is completely and definitively useless.
In other words if wordpress wouldn’t be accessible from the internet, you would have an “easy to install application” that nobody want.
From every applications i have (owncloud, drupal, ampache, etc) there is always specific points on their configuration documentation making them the way they used to be : Made for the internet.
So yes that may not the part of the installation of wordpress but isn’t it the most important part ? In my own opinion, the answer is yes. And by the way, wordpress is not accessible by this site enabled of apache by the way.
