Eh it's a bit more than that. We can apply classic physics to microscopic scales. We do it all the time.
For example, when we are determining the Zeeman Effect we are simply using E = hF, a deterministic eqn, to find photon frequency F when some level of energy E is absorbed by electrons in a shell. And photons are about as microscopic as one can get.
The Zeeman results are not considered QM because the results we get, the frequency, are deterministic. There is no uncertainty in those values. When electrons jump to a higher energy level by absorbing photon energy, there will be a spectrometer line of absorption at that frequency...not a bit more, not a bit less. It's deterministic.
Quantum physics is more about what we measure, the observables, and how we interpret the physical processes, based on those observations. And because we can only measure what we can detect (observe) there is some uncertainty in the process that is creating that observable. It's that uncertainty, like the Heisenberg Uncertainty Principle, that is the hallmark of quantum physics.