Board Thread:Theories and Speculation/@comment-25093611-20160221130833/@comment-25122992-20160221164729

I think that the issue is not mastery, but suitable body. As we could see at the Mount Myoboku, there were a lot of people, who tried to master senjutsu, but failed and got turned into stone frogs. This parallels with the 10% rate of adaptation to the CS injected into the body (which is actually a senjutsu too). Kabuto also said something about Oro's need of suitable body to master SM at the Ryuchi Cave. So I have a theory, that in ninja world there are 3 kinds of people: completely unsuitable for senjutsu (the one who got turned into stones + one who died after obtaining CS), adaptable for senjutsu (those who can potentially master senjutsu with enough training and can use CS - Naruto, Sasuke and other known senjutsu/CS users) and naturally prone to senjutsu (these are Jugo and his clan, who have the bodies able to absorb natural energy without any training, oft unknowingly even for themselves).