Why isn't a tutoriel replacement for Sony Xperia SP

Pabblo, that is the beauty about ifixit. Here you can make your own guides. You can not expect ifixit as a company to spend thousands of dollars and purchase every phone possible, just to make guides for us. There is an expectation that we all, as a community help out. So, I suggest something like this video for you. It is not the greatest, but is does show how to disassemble an SP. When you do your battery replacement, make a guide and post it on here. That way our ifixit community grows and others, like yourself will be helped. Best of luck to you.