That has nothing to do with concrete5, that's a common questions related to your server configuration.

In short: If all the processes of a hosting account (a single user on a machine with a ton of other users/hosting), run with the same user, there's no need for that.

If PHP is running as "user_dhammadude" as well as apache, both processed can access all the files. That's usually the case when you work with FCGI while it's probably the opposite if you're using mod_php.