Why is CD / DVD Sharing so incredibly limited

Take a look at this technote:

http://support.apple.com/kb/HT5287?viewlocale=en_US&locale=en_US

I am refering in particular to:

Note: These types of discs or activities are not supported by DVD or CD sharing:

• DVD movies.
• Audio CDs.
• Copy protected discs such as game discs.
• Install discs for an operating system such as Microsoft Windows (for use with Boot Camp), or Mac OS X.
• Burn a CD or DVD

So it appears you can load software but that is about it. Why? What is the technical limitation (speed of connection) that makes this so very UNuseful.

Bryan