Board Thread:Naruto Discussions/@comment-28849742-20170102125315/@comment-734582-20170103090314

Elveonora wrote: Exaçtly, because every non elemental technique was said to have a different ratio of physical and mental energies, hence there has to be more to it. I think it's simply a deeper control over chakra.

Each shinobi can mould chakra, but it seems few have control over the ratios. Yin release is control over the mental part (creating images, ideas, giving form), whereas Yang is control over the physical part (changing size, healing). Unlike regular chakra, Yin or Yang release can bring out that component's special properties. So Yin and Yang release change the fundamental properties of chakra.

Similarly, Six Paths Yin and Yang is a deeper control over Six Paths chakra (which seems to take the Soul and Blood/lifeforce rather than chemical energy and thoughts).

So yin-yang can nullify ninjutsu because it attacks the basis of ninjutsu, namely the chakra itself.

So to be clear, every shinobi can mould chakra, but it takes special control to adjust it's properties. Simultaneous control (yin-yang release) grants both abilities (ability to project thoughts and make them real).

Genjutsu is Yin Release (control over thoughts). Medical Ninjutsu can be both Yin and Yang (health doesn't just depend on the presence of e.g. cells but also on the structure, hence Yin and Yang).