Earlier quoted context omitted.
玉 was a variant of 王 (king)[0] thus king in walls (国), it's definitely NOT "only jade". [0]: https://zh.m.wiktionary.org/zh/%E7%8E%89
Then why not just put 王 in the box rather than 玉? As far as I can tell the 王 glyph predates the invention of 玉, and the purpose of this new glyph was to distinguish 玉 from 王. Also isn't a land within borders still a better analogy for a country than a king within walls? Walls bounding a king seems more like a palace.
Why isn't "business" a measure of how busy you are?
Why isn't "waterboarding" analogous to "snowboarding" and "sandboarding"?
(As an engineer I hate these peculiarities and I'm all for fixing them but the majority of the world tends to want to stick to the not-necessarily-logical definitions.)