Why didn't Ke Li recommend Huang Yuanyu?

Vulcan school and Huang Yuanyu have the same virtue, which can be easily cured quickly, but they have not been eradicated. I can't see what Yang has. In other words, it's a shot in the arm. This medical theory treats a disease, and you should never stop taking medicine. Once you stop taking the medicine, you will die faster. Suitable for the impetuous atmosphere of the present society.