question about Version-Control

Hi,

There's someyhing about I've have questions : when a user calls the VERSION-CONTROL method on a versionable resource, it performs 3 operations :
    - creation of a new version history,
    - conversion of the versionable resource in version controlled resource,
    - creation of a new version by copy of the versionable resource (content and properties).

My question is : why doing a copy of the version controlled resource ? why duplicating it ?
It is not enough, just keeping it, and creating the first version after checking it out, modifying it, and checking it in ?

Thanx in advance for answering at this (simple) question !