True Words are a rather special "Extraordinary Power."
It is not the power of the user themselves, but a kind of borrowing, a way to carry and "control" the special power of a superior using one's own body as a vessel.
But the power of a superior couldn't possibly be infinite, and even less likely to be lent out endlessly without any reason.
Using True Words is a skill, and even more so a "qualification," or perhaps, also a kind of "transaction."
Deities usually only open "qualifications" to their devout followers, and mostly with many troublesome and tedious restrictions, with additional costs for continued use.
Even the most liberal Abyss True Words required sacrifices and many prerequisite conditions when Lu Ping'an and Zhi Xi were learning them.
Zhi Xi relied on Abyss Transformation, while Lu Ping'an on Abyss knowledge (Almight Taboo Knowledge); in some sense, they were both people of the Abyss, but what does the Snake King have now?
