It is far easier to source a text than to gather
sources and write a
new article from scratch. Sourcing is grunt work where writing a new
article requires creativity and whatnot.
That kind of thinking is one of the biggest problem with Wikipedia at
the moment. Sourcing should always come *before* writing. The source
is where the information came from, that's what "source" means, so you
have to have the source before you can write the article. Adding
sources afterwards is a way of fixing a problem - unsourced articles -
it should not be a part of the standard process of writing articles.
The problem should never be created in the first place.