"The body is mysterious and unfathomable, within it is a gate called the Gate of Creation. Each person is unique, and when the gate opens, humans and Gu unite as one. The Gu can transform and be transformed; the Gu poison is self-contained."
What does this mean?
The human body has a gate called the "Gate of Creation," which is the most crucial aspect of Gu technique. If this gate isn't opened, Gu is Gu and human is human. Forcing the human and Gu to merge can only result in the power and drawbacks of the Gu rushing together with the human, turning them into what? A monstrous hybrid neither human nor Gu!
What exactly would it look like?
It can be referenced by the earlier Gushan elder, who played with Corpse Gu and turned himself into a monster neither human nor ghost.
This is called gaining the power of the Gu while also having to bear the cost of its backlash.
