It was done because it was seriously confusing new users, and people were creating Community Wiki posts when they didn't need them. Note that you don't need a mod to create them for you:
What are "Community Wiki" posts?
How does a post become a Community Wiki post?
There are several ways a question or
answer can enter community wiki mode,
and most of these ways will occur
automatically based on the rules of
the system.
Posts enter community wiki mode when
one of the following happens:
- The body of the post has been edited by at least five (5) different
users.
- The post has been edited ten (10) times by the original owner.
So if you edit your own question 10 times, you get a CW question!