I am looking to install mediawiki on a production server (after doing a test on a development one). I could not really understand why the default location for the mediawiki files is /var/lib/mediawiki. I would have thought /var/www would've made more sense.

I did some research and in http://people.canonical.com/~cjwatson/ubuntu-policy/policy.html/ch-customized-programs.html#s-web-appl it says the following

Web Document Root

Web Applications should try to avoid storing files in the Web Document Root. Instead >they should use the /usr/share/doc/package directory for documents and register the Web >Application via the doc-base package. If access to the web document root is unavoidable >then use

/var/www

Can anyone explain why this is please?