Because, you know, words are just words.
Until you're trying to explain them to someone who doesn't speak the same language, and suddenly they're like, "What do you mean? What are you even saying?!"
And you're all, "I'm saying, uh, the sky is blue, and also, uh, it's not actually blue, it's more like, uh, a shade of grey, but also, uh, it's also kind of, uh, blue-ish?"
Miscommunication Idioms