WordPress MU

.. but my HS teacher said the only dumb questions on earth is the one that's not asked. So I asked "So, would it be a dumb question to ask if I could take over the class as the teacher?"

then he replied, "ok so ... there are only TWO dumb questions on earth"

Here's my question.
I looked the structure of wordpress and was thinking, "why even bother using WP MU?" For example, if had a server with multiple domains names (i.e. parked domains) and did something like this in wp-config.php in regular WP:

switch($_SERVER['SERVER_NAME'])
{
   case "somedomain.com":
     require_once("wp_config.somedomain.php"); // this file would include DB settings
     break;
   case "someotherdomain.com":
     require_once("wp_config.someotherdomain.php");
     break;
}

Wouldn't this be almost identical to WP MU?

Sure some functionalities would be lost, but wouldn't this suffice for most multi-blog sites?

Can someone enlighten me?

Depends on what you want to do. that (or near enough to it) works just dandy if you're setting up a handful of blogs that you alone manage.

Not so much if you have, say, a hundred. With different admins.