>> So million and billion are close because they are spelled similarly and they deal with the same conceptual "thing.

Citation needed. Is this based on any sort of formal linguistic/anthropological reasoning or just like, your opinion?

Also, the article's whole point is "people are bad at numbers" and your argument that "linguistically, all numbers close" isn't really true. Why don't rhyming words in English feel "close"? Also, "duck" and "fuck" are both verbs involving a thing you would do with your body, so why isn't that closeness?

If you're going to point out that language feels arbitrary by making arbitrary points, you're going to be "right" but you're not actually saying much. Language can be both specific and arbitrary (it's a means of expressing both objective and subjective concepts) so an argument in favor of doing your best when seeking to be objective seems pretty reasonable.