Why would Android delete Facebook Home?

Does Google want this? No, they do not. But Mountain View lets (encourages?) their OEM’s and carriers to mess with the pure Android experience so they have to let Facebook do it too if customers so desire. And why not? In the most recent versions of Jellybean, you can make Google Currents your lock screen. OEMs have long had access to the way your homescreen looks. Why shouldn’t other vendors have access to these functions?