Yea. It's still weird as hell to call rice a vegetable as if that's meaningful. Doubly weird to consider rice's vegetable-ness as leading to its carbness.

Most of the rice plant is just fiber, nutritiously.

Fiber is a carbohydrate too, you know. What non-vegetable source of carbohydrates do you know of? As far as I'm aware, human dietary carbohydrates overwhelmingly come from (1) grass; (2) potatoes; (3) fruit; or (4) sugar beets. There is a reason for this: carbohydrate is the basic structural material of plants in the same way that protein is the basic structural material of animals.

I guess you could call honey an animal source of carbohydrates. It's not exactly a huge part of any non-hunter-gatherer's diet. And the bees have to make it from flowers.