Except it's not. Autophagy as a process happens at the cellular level but the whole reason it's important is because it has emergent ramifications for the entire living organism, impacting on metabolism, senescence, carcinogenesis and a number of other endpoints that operate at organismal scale. Your characterisation of this as "fundamental biology" obscures this emergence.

Appropriateness aside, I think the real reason we don't have a Nobel for Biology is probably a result of the fact that Alfred Nobel cared more about the pursuit of knowledge for the betterment of the human condition, rather than for its own sake. I imagine he learned the limitations of the latter approach the hard way through personal experience considering his most (in)famous invention...