Why would anyone ever assume that biology obeys an entirely artificial distinction between classical and quantum mechanics devised from human ignorance billions of years after evolution began?
The best description is the simplest one being able to describe all related phenomena. So unless you have a very good reason, it wouldn't be helpful to start from the standard model of particle physics.
On the other hand, if you tried the classical theories and notice that there are things unaccounted for, then you go and look for more detailed theories to apply to your problem. That's the normal way you do research and that's what happened here.