> One could retort to the original title saying all matter is, in fact, "quantum".

Quantum matter has a specific meaning in condensed matter physics. It's anything where you can't approximate the system's behavior with classical physics at a macroscopic level. IE, the optical properties of metals are classical, but the electrical properties of topological insulators are not.

It is a bit like saying that all ecologists are chemists. Animals are, in fact, big sacks of chemicals, but that's not really the point.