User blog comment:Rupert Giles/Introducing Updated Global Navigation/@comment-5645428-20141023130257/@comment-452-20141028180628

I like currently implementation on the new search bar on CC with the drop down to choose.

But changing the default to search all wikis instead of the current wiki, or to mix off-wiki results in with this-wiki results both sound like terrible ideas, which will cause much confusion.

edit: Specifically, this may cause users to inadvertently leave the wiki they were viewing, end up on a wiki about a different subject, get confused, and stop viewing Wikia at all.