As a law enforcer, Xia Qin could be considered a typical altruist, yet her ability was purely selfish.
This was the norm for most professionals... It wasn't just about personal compatibility; the "inner body" is the area most susceptible to interference by will and power. After most abnormal abilities awaken, the first thing they influence is oneself.
The abundance of the Transformation System is inevitable; the Beastmen's prevalence and their strength above the average line are the most obvious manifestations.
The Rule System is the least numerous and weakest initially because "interfering with other things (setting rules)" is much more difficult than "changing oneself."
Meow represents the pinnacle of the Transformation System, capable of converting between the physical body and the spirit body at will. The most challenging step of Rule-level advancement, "sublimation of the physical body," poses no difficulty to her.