And yet you don't bat an eye at "sub-atomic". Welcome to !!language!!.
Well right now computers don't look at things on an atomic level, a transistor is a single unit, and isn't made of anything smaller, as far as the computer as a unit cares. This way of processing looking as units smaller then a conventional chemical atom, so things smaller then atoms, so sub-atomic. Problem?
You were complaining that the "quantum" in "quantum computer" doesn't meet your understanding of the term from some context other than quantum physics. Lest you forget, once upon a time "atom" meant an indivisible unit. With that understanding of the word, "sub-atomic" is a contradiction. The term was justifiably applied to physical units once thought to be atomic, and later discovered not to be. By that time, the term was established technical jargon, and "atomic" can refer to anything having to do with atoms or the study of atoms. It's much the same with quantum physics. The behaviors of things which were unexpectedly found to come in discrete quantities turned out to also include things like superposition and entanglement. These aren't quanta of anything, but still fall under the broad banner of quantum physics. And it is these that are responsible for the unique properties of quantum computers.
The point is, language isn't static. It changes over time and according to context. You can't criticize a term like "quantum computer" without considering the context it comes from.
Or, in dwarven metaphor: People often don't notice the difference between language and !!language!!. If you pick up the wrong one, you may find your lips have suddenly melted off. The moral is, I dunno, always consult the language files?