Board Thread:Theories and Speculation/@comment-24824859-20150704165201/@comment-734582-20150718152547

GreatestSin wrote: obito and his afterlife-kamui... Uhm no, it's fairly easy to explain. It works exactly like Edo Tensei, which allows a user to come back from death and overwrite the target body with it's own powers. What Obito did was essentially a highly advanced Edo Tensei that only affected Kakashi's eyes, allowing him to transform them and give them his Kekkei Genkai. Afterwards it's effect faded (because he lost his ties to the human world) and so the sharingan was gone.

By your explanation, Edo Tensei is a jutsu that can not exist, but it clearly does which invalidates your arguments.